CA2070145A1 - Process for passivating metal surfaces to enhance the stability of gaseous hydride mixtures at low concentration in contact therewith - Google Patents
Process for passivating metal surfaces to enhance the stability of gaseous hydride mixtures at low concentration in contact therewithInfo
- Publication number
- CA2070145A1 CA2070145A1 CA002070145A CA2070145A CA2070145A1 CA 2070145 A1 CA2070145 A1 CA 2070145A1 CA 002070145 A CA002070145 A CA 002070145A CA 2070145 A CA2070145 A CA 2070145A CA 2070145 A1 CA2070145 A1 CA 2070145A1
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- Canada
- Prior art keywords
- metal surface
- gas
- gaseous
- hydride
- passivating agent
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B5/00—Drying solid materials or objects by processes not involving the application of heat
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C8/80—After-treatment
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C10/00—Solid state diffusion of only metal elements or silicon into metallic material surfaces
- C23C10/06—Solid state diffusion of only metal elements or silicon into metallic material surfaces using gases
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C8/02—Pretreatment of the material to be coated
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
- C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Organic Chemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Molecular Biology (AREA)
- General Engineering & Computer Science (AREA)
- Filling Or Discharging Of Gas Storage Vessels (AREA)
- Silicon Compounds (AREA)
- Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
- Preventing Corrosion Or Incrustation Of Metals (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A process for passivating a metal surface to enhance the stability of a gas mixture containing one or more gaseous hydrides in low concentration in contact therewith, which comprises:
a) purging gas in contact with said metal surface with inert gas to remove the purged gas, b) exposing the metal surface to an amount of a gaseous passivating agent comprising an effective amount of a gaseous hydride of silicon, germanium, tin or lead and for a time sufficient to passivate said metal surface, and c) purging said gaseous passivating agent using inert gas.
A process for passivating a metal surface to enhance the stability of a gas mixture containing one or more gaseous hydrides in low concentration in contact therewith, which comprises:
a) purging gas in contact with said metal surface with inert gas to remove the purged gas, b) exposing the metal surface to an amount of a gaseous passivating agent comprising an effective amount of a gaseous hydride of silicon, germanium, tin or lead and for a time sufficient to passivate said metal surface, and c) purging said gaseous passivating agent using inert gas.
Description
2~7~
TITLE OF T~E INVENTION
PROCESS FOR PASSIVATING METAL SURFACES
To ENHANCE THE STABILITY OF GASEOUS
HYDRIDE MIXTURES ~T LOW CONCENTRATION
IN CONTACT THEREWITH
~ ACKGROUND OF ~HE INVE~TION
Field o~ the Invention:
The present invention relates to a process for passivating metal surfaces to enhance the stability of gaseous hydride mixtures at low concentration in contact therewith.
Descri~tion of the 8ackqround:
In the electronics industry, and in view of environmental considerations, there is an important need for stable gas mixtures containing low concentrations of gaseous hydrides in the ppb to ppm range. The standard practice in industry is to prepare such mixtures in compressed gas cylinders, in which such mixtures are often stored for extended periods of time.
However, due to reactions between gas mixtures containing such amounts of gaseous hydrides and the metal surfaces of contalners containing these mixtures, it is very difficult to stabilize the same.
One approach to overcoming thi~ instability and to maintaining a constant gas mixture concentration is to minimize the contact time between the low concentration hydrides and metal container~ by ~toring a high concentration mixture in the cyllnder and then diluting immediately before -2- 2~7~
use. Unfortunately, however, in many instance~, it i8 deqirable, if not neces6ary, to store the gas mixture~ in metal cylinder~ for extended periods of time.
Another approach for maintaining a constant gas mixture concentration of low concentration hydride~ iR saturation passivatlon. In this technique, the container 1B sub~ected to several cycle~ of evacuating and filling with a much higher concentration of the same gaAeous hydride, prior to being filled with the low concentration hydr~de ~ixture of lnterest.
This procedure is repeated several times based upon previous e~pirical studies. This technique iB of l~mited usefulness, however, a~ a higher concentration of the same hydride must be used for conditioning the container, and it is very disadvantageous to handle large a~ounts of toxi~ gases, such as arsine, during the process.
Thu~, a need continues to exist for a passivat~on proces~
which i~ suitable for stabilizing gaseous hydride mixtures, which avoids the drawbacks of the conventional approachec described above.
SUMMARY OF THE INVENTION
Accordingly, it is an ob~ect of the present invention to provide a process for pas~ivating a ~etal surface to enhance the ~tability of a gas mlxture conta~ning gaseous hydride~ in low concentration in contact therewith.
TITLE OF T~E INVENTION
PROCESS FOR PASSIVATING METAL SURFACES
To ENHANCE THE STABILITY OF GASEOUS
HYDRIDE MIXTURES ~T LOW CONCENTRATION
IN CONTACT THEREWITH
~ ACKGROUND OF ~HE INVE~TION
Field o~ the Invention:
The present invention relates to a process for passivating metal surfaces to enhance the stability of gaseous hydride mixtures at low concentration in contact therewith.
Descri~tion of the 8ackqround:
In the electronics industry, and in view of environmental considerations, there is an important need for stable gas mixtures containing low concentrations of gaseous hydrides in the ppb to ppm range. The standard practice in industry is to prepare such mixtures in compressed gas cylinders, in which such mixtures are often stored for extended periods of time.
However, due to reactions between gas mixtures containing such amounts of gaseous hydrides and the metal surfaces of contalners containing these mixtures, it is very difficult to stabilize the same.
One approach to overcoming thi~ instability and to maintaining a constant gas mixture concentration is to minimize the contact time between the low concentration hydrides and metal container~ by ~toring a high concentration mixture in the cyllnder and then diluting immediately before -2- 2~7~
use. Unfortunately, however, in many instance~, it i8 deqirable, if not neces6ary, to store the gas mixture~ in metal cylinder~ for extended periods of time.
Another approach for maintaining a constant gas mixture concentration of low concentration hydride~ iR saturation passivatlon. In this technique, the container 1B sub~ected to several cycle~ of evacuating and filling with a much higher concentration of the same gaAeous hydride, prior to being filled with the low concentration hydr~de ~ixture of lnterest.
This procedure is repeated several times based upon previous e~pirical studies. This technique iB of l~mited usefulness, however, a~ a higher concentration of the same hydride must be used for conditioning the container, and it is very disadvantageous to handle large a~ounts of toxi~ gases, such as arsine, during the process.
Thu~, a need continues to exist for a passivat~on proces~
which i~ suitable for stabilizing gaseous hydride mixtures, which avoids the drawbacks of the conventional approachec described above.
SUMMARY OF THE INVENTION
Accordingly, it is an ob~ect of the present invention to provide a process for pas~ivating a ~etal surface to enhance the ~tability of a gas mlxture conta~ning gaseous hydride~ in low concentration in contact therewith.
-3- 2~7~
It is also an object of th~s invention to provide a process for passivating a metal surface, which is advantageous for treating any metal surface, particularly those which are used to make gas storage cylinders, conduits, container~, pipes, tank truck storage rigs or railroad tank storage cars, for example.
It is, in particular, an ob~ect of the present inventlon to provide a process for passivating a metal surface, which is particularly advantageous for treating metal compressed gas storage cylinders.
~ he above ob~ects and others which will become more apparent in view of the following are provided by a process for passivating a metal surface to enhance the stability of a gas mixture containing gaseous hydrides in low concentration in contact therewith, which entails:
a) purging gas in contact with said metal surface with inert gas to remove the purged ga~, b) exposing the metal surface to an amount of a gaseous pas3ivating agent comprising an effective amount of a gaseous hydride of silicon, germanium, tin or lead, and for a time sufficient to passivate said metal surface, and c) purging the pa~sivating agent u~ing inert gas.
~RIEF DESCRI~TION OF THF ~RAWINGS
Figure 1 illustrates a schematic diagram of a flow system in accordance with the present invention.
2070~
Figure 2 qraphically illustrates the relationship between trapping time and 108~ of l ppm AsHJAr in 316 ~ ~tainles3 steel tubing.
~ETAILED ~ESCRIPTION ~F THE PREFERRED EMBODIMENT$
In accordance with the present invention, a proce6s is provided for passivating a metal surface to enhance the stability of a ga~ mixture conta~ning gaseous hydrides in low concentration in contact therewith, such as arsine, phosphine or stibine.
At present, passivation is used to improve the corrosion resistance of metal particles and steel surface3 for very particular applications. For example, WO ~9/12887 describe~ a silane passivation process on metal particles, which improve~
the corrosion resiatance against metallic oxidation, and GB
2,107,360 ~ describes a silane passivation process for steel surfaces for i~proving corrosion resistance in a carbon dioxide-rich environment at high temperature and pressure.
However, neither of these disclose or suggest a process for stabilizing a gas mixture composition as in the present invention.
In accordance with the present process, any metal surface may be treated 60 a~ to enhance the stability of gas mixture~
containing gaseous hydrldes ~n low concentration ln contact therewith. The metal surface may be, for example, metal tubing, metal valves or metal compressed gas storage -5- 207~
cylinders. However, any type of metal surface may be 80 treated.
For example, in accoxdance wlth the present invention, any ~etal may be passivated, in particular those which are u~eful in making gas storage cylinders, condults, containers, pipe~ and any type of storag~ ~ean~ including railroad tank storage car6 and tank truck traller rigs. For example, metals such as iron, steel and aluminum may be passivated in accordance with the present invention.
The present invention may, for example, be advantageously used in the treatment of various steels and alloys thereof, such a~ ferr~te steelc, austenitic steels, stainless steels and other iron alloy~, and is particularly advantageous in the treatment of stainless steels. However, other types of metal~
may be 80 treated.
Generally, the present invention is used to passivate a metal surface using relatively non-toxic gaseous hydride~ to enhance the ~tability of gas mixtures containing gaseous hydrides in low concentration.
As used herein, the term "relatively non-tox~c gaseous hydrides" includes the silicon hydrdes, germane hydrides, tin hydrides and lead hydride. The toxic gaseous hydrides such as arsine or pho~phlne are avoided.
Of part~cular usefulne~s are 6ilicon hydrides of the general formula Sin H2~2, such as SiH~, Si2H6 and Si6H~.
-6- 2~7~
However, other hydride~ ~uch as Ge2HS, Ge~20, SnH~, SnH6 or PbH~.
may be used.
In the above for~ula for cilicon hydrides, n is generally from 1 to about 10. However, n can be a higher value a~
silicon hydrides are known to exhibit catenation. See ~dvanced InLoraani ChemistrY, Cotton and Wilkin~on, Third Edition.
AB used hereln, the phrase "ga~eous hydrides in low concentration" generally means gaceous hydrides of a concentration of from about 10 ppb to about 10 ppm. More preferably, the concentration is about 50 ppb to about 5 pp~.
Most preferably, however, the concentration about 100 ppb to about 1 ppm.
In accordance w~th the present invention in order to pa3~ivate a ~etal surface to enhance the gtability of a ga~
~ixture containing gaseous hydrides in low concentration in contact therewith, it is first necessary to purge the gas or gas mixture initially in contact with the metal surface with inert gas to remove the purged ga As an inert purging gas, any gas which is generally chemically non-reactive may be used. For example, the so-called noble gases, such as krypton, xenon, helium, neon and argon may be used. However, other ga~es such ae hydrogen and nitroqen may be u~ed.
Generally, the inert purging ga~ will be passed over the metal surface for a ti~e and in an amount ~ufficient to re~ove ~ub~tantially all of the pury~d gas. Typlcally, the purging -7- 2~7~
gaR is pa~sed over the metal surface, or through à volume defined by a contlnuous metal surface, such as a compressed gas ~torage cylinder, for anywhere from ~everal ~econds to up to about 30 minutes at from 1 to about 3 atmosphere~ of pressure. However, higher pressures may be u~ed, if desired.
In accordance with the present invention, nitrogen ha3 been found to be advantageous as an inert purqing gas, although other inert gases may be used.
After purging the gas in contact with the metal surface, the metal ~urface 15 then exposed to an amount of passivating agent containing an effective amount of one or more gaseous hydride~ of silicon, germanium, tin or lead, and for a time sufficient to pas~ivate the metal surface.
Generally, the higher the concentratlon of passivating ~-?
agent used, such as silane, the shorter the exposure time required. However, passivating agent concentration~ of as low a~ 1 ppm may be used, or as high as 100%. For example, if a very low concentration of silane is used, exposure times in excess of 80 hours are usually required. Generally, exposure timee of about 100 hours are typically used for dilute passivating agents. However, if relatively pure passivating agent i~ used, for example, generally les~ than 60 minute~
exposure t~me i~ required, preferably less than 30 minutes.
A~ de~cribed above, the phrase "pure passivating agent"
means that the pasRivating agent used is the pure gaseou~
hydride of one or more ~illcon, germanium, tin or lead.
2~7~
While any concentration of passivating agent may be used, it is ganerally desirable to use a concentration in the range of about 0.01% to 20% by volume. It is preferred, however, to use a concentration in the range of about 0.01% to 5% by volume. With such concentrations, an exposure time of from about 1 to 24 hours i8 generally required. Generally, for larger metal ~urface~, such a~ vessels, larger volumes of passivating agent ~ay be used.
In accordance with the present invention, substantlally all of the purged ga~ is displaced or removed by the inert gas .
As used herein, the phrase "substantially all of the purged gas" means that the purged ga~ is removed to an extent of above 99% by volume.
Generally, the purged gas is air, however, other gases or gas mixtures, such as mixtures mainly containing nitrogen and oxygen, may be purged in accordance w~th the present invention.
Generally, the exposure of the metal surface to the passivating agent may be effected at from very low temperatures of about -20-C to up to right below the gaseous hydride decomposition temperature of the one or more gaseous hydrldes in the passivating agen~. For example, the decompo3ition temperature of ~llane is 250 C. However, it is generally preferable to effect the exposure at from about lO-C
to about lOO-C. It i~ more prefersble to effect the 9 2 ~ 7 ~
passivating agent expo~ure at from about 20-C to about 50-C.
However, it ls most advantageous to effect the expoeure at about 25-C.
Although the exposure may be effected at high temperature~, the gas phase reaction of the one or more ga~eoue hydride of the passivating agent, euch a~ silane, i8 preferably kept to a minimum to avoid the formation of particle~. Generally, this means at a temperature of less than the pa~sivating agent gaseoue hydride decomposition temperature.
After subjecting the metal surface to treatment with passivating agent, the latter is, itself, purged with an inert purging gas, such as nitrogen. However, the noble gase~ a~
described above may be used.
The present invention also provides an optional fourth step in wh~ch the metal surface is then exposed to an oxidizing gas in order to stabilize the adsorbed pas~ivating agent on the metal surface. As an oxidizing gaB ~ gaB mixtures containing nitrogen and oxygen may be used, for example.
Generally, oxidizing gas ~ixtures may b~ used which are capable of oxidizinq the adsorbed passivating agents to an inert oxidized form. For example, gas mixtures contalning from about 1 to 10% volume of oxygen in nitrcqen may be advantagesusly used when using such mixtures to oxidize the adsorbed passivating agent, metal surface exposure timee of fllm about 30 eec. to about 3 ~inutes are generally used.
-lO- 20701 ~
However, shorter or longer exposure time~ may be us2d as required.
In general, the oxidation step may be effected at the same temperatures as used for the passivation step, with temperatures of from about lO-C to about lOO C being preferred, and with temperaturQ~ of from 20-C to about 50-C
being most preferred.
In accordance with this a~pect of the pre~ent invention it has been discovered that adsorbed gaseous hydride may be desorbed very slowly over a period of time thus reducing the effectiveness of the passivation treatment over time. By oxidizing the adsorbed passivating agent containlng a gaseous hydride, such as silane, for example, an inert compound, such as sio2, may be formed. Hence, the oxidation ctep provides a means to stabilize the pa~slvated metal surface for long term use.
Figures 1 and 2 will now be described in more detail.
Flgure 1 provide~ a schematic flow diagram using mass flow controllers, an arsine permeation device, valves and port valves A and B in fluid connection. This apparatus is conveniently used to test the stability of gaseou~ hydrides, a~ measured by an inductively coupled plasma spectrophotometer. However, other detectlon means known to those skilled in the art may be used instead.
Figure 2 illustrates a summary of stability data from sample~ A, ~ and C a~ defined hereinbelow in the sxample. In -11- 2~7~ 3.~
particular, the 1 ppm treatment (sample C) failed to passivate the metal surface after 69 hour~ of exposure. Generally, at such low concentrations, in exces~ of 70 hour~ of exposure is required, preferably at least 80 hours of expo6ure.
The pure silane treatment (sample B) effected surface passivation in le~ than 30 mlnutes of exposure. Sample A iB
a controlled sample.
Generally, in accordance w~th the present invention, the ga~eous hydride treatment is effected to passivate 6ubstantially all of the metal surface. ~B u~ed herein, the term "~ubstantially all~ means that at lea~t 90% of the metal surface in contact with the gaseous hydride is passlvated.
However, it i~ preferred if at least 99% of the metal surface in contact with the gaseous hydride is passivated. It is particularly preferred if at least 99.9% of the metal surface in contact with the gaseou~ hydride is passivated.
The present invention will now be further illustrated by reference to certaln examples which are provided for purposes of illustration and are not intended to be limitative.
Example In order to demonstrate the effect of the present invention on ~etal surfaces, a 1/4" ID sta~nless steel tube was used.
Three identical ~amples (A, B and C) of 1/4" ID stainle~s ~teel tubing~ were exposed to amblent air under the ~ondit~on~
-12- 20701~
typical in the preparation of gas handling and storage eguipment. It is known that under such exposure condltlons, the stability of mixtures is very poor. All of the sample~
were then purged with dry N2 gas at room temperature. Sample A
~erved as a controlled sample. Sample B was then treated with flowing pure silane for 30 minutes at room temperature and sample C wa~ purged with 1 ppm silane for 72 hours, followed by purging with dry air, according to the condltions de~cribed below.
The 6tability of hydrides in the ~o prepared samples A, B
and C was tested in a setup as shown ~n Figure 1. The tube was filled with argon gas contalning 1 ppm arsine. This gas was kept in the tube by means of the valve 2 in Figure 1 for var~ oU8 periods of time. ~fter that, the gas was introduced into a device capable of meaguring the concentration of hydride remaining in the gas. In this example, the device is an inductively coupled plasma spectrophotometer. However, other detection means may be used. The ratio of initial fill concentration to final concentration was used to measure the gas stability. The results for a typical test with arsine are shown in Figure 2.
Additionally, the present lnventlon also provides storage mean~ for a gas or gas mixture, which means at least has an interior metal surface thereof which ha3 been passivated.
However, the 6torage means may be completely made of metal.
Preferably, the storage means ls co~pressed ga8 6torage -13- 2Q70~5 cylinder. However, the storage means may be a mobile storage means, such as a tank tractor traller rig or a railroad tank car.
Thus, the present invention provide~ storage means havlng at least an interior metal surface thereof which i6 passivated, thereby enhancing the stability of a gas mixture containing one or more gaseous hydrides in low concentratlon when in contact therewlth. As used herein, the term "passi~ated" means that the internal metal surface of the storage means has been sub~ected to the pre~ent passivation proce~s and i~ thus unable to react with gases or gas mixtures stored therein which contain low concentrations of gaseous hydrides. In accordance with the present inventlon, it is advantageous if the passivating agent used i8 a silicon hydride of the formula Sin H2~Z, wherein n ~g about 1-10, more preferably n is 1.
It is, however, particularly preferred if the passivated ~torage cylinder whose internal surface has been pas~ivated with ga6eous hydride passivating agent in accordance with the present proces~.
Having described the present invention, it will now be apparent to one of ordinary sklll ln the art that many changes and modlficatlon~ may be made to the above embodiments without departing from the 6pirit and the scope of the present invention.
It is also an object of th~s invention to provide a process for passivating a metal surface, which is advantageous for treating any metal surface, particularly those which are used to make gas storage cylinders, conduits, container~, pipes, tank truck storage rigs or railroad tank storage cars, for example.
It is, in particular, an ob~ect of the present inventlon to provide a process for passivating a metal surface, which is particularly advantageous for treating metal compressed gas storage cylinders.
~ he above ob~ects and others which will become more apparent in view of the following are provided by a process for passivating a metal surface to enhance the stability of a gas mixture containing gaseous hydrides in low concentration in contact therewith, which entails:
a) purging gas in contact with said metal surface with inert gas to remove the purged ga~, b) exposing the metal surface to an amount of a gaseous pas3ivating agent comprising an effective amount of a gaseous hydride of silicon, germanium, tin or lead, and for a time sufficient to passivate said metal surface, and c) purging the pa~sivating agent u~ing inert gas.
~RIEF DESCRI~TION OF THF ~RAWINGS
Figure 1 illustrates a schematic diagram of a flow system in accordance with the present invention.
2070~
Figure 2 qraphically illustrates the relationship between trapping time and 108~ of l ppm AsHJAr in 316 ~ ~tainles3 steel tubing.
~ETAILED ~ESCRIPTION ~F THE PREFERRED EMBODIMENT$
In accordance with the present invention, a proce6s is provided for passivating a metal surface to enhance the stability of a ga~ mixture conta~ning gaseous hydrides in low concentration in contact therewith, such as arsine, phosphine or stibine.
At present, passivation is used to improve the corrosion resistance of metal particles and steel surface3 for very particular applications. For example, WO ~9/12887 describe~ a silane passivation process on metal particles, which improve~
the corrosion resiatance against metallic oxidation, and GB
2,107,360 ~ describes a silane passivation process for steel surfaces for i~proving corrosion resistance in a carbon dioxide-rich environment at high temperature and pressure.
However, neither of these disclose or suggest a process for stabilizing a gas mixture composition as in the present invention.
In accordance with the present process, any metal surface may be treated 60 a~ to enhance the stability of gas mixture~
containing gaseous hydrldes ~n low concentration ln contact therewith. The metal surface may be, for example, metal tubing, metal valves or metal compressed gas storage -5- 207~
cylinders. However, any type of metal surface may be 80 treated.
For example, in accoxdance wlth the present invention, any ~etal may be passivated, in particular those which are u~eful in making gas storage cylinders, condults, containers, pipe~ and any type of storag~ ~ean~ including railroad tank storage car6 and tank truck traller rigs. For example, metals such as iron, steel and aluminum may be passivated in accordance with the present invention.
The present invention may, for example, be advantageously used in the treatment of various steels and alloys thereof, such a~ ferr~te steelc, austenitic steels, stainless steels and other iron alloy~, and is particularly advantageous in the treatment of stainless steels. However, other types of metal~
may be 80 treated.
Generally, the present invention is used to passivate a metal surface using relatively non-toxic gaseous hydride~ to enhance the ~tability of gas mixtures containing gaseous hydrides in low concentration.
As used herein, the term "relatively non-tox~c gaseous hydrides" includes the silicon hydrdes, germane hydrides, tin hydrides and lead hydride. The toxic gaseous hydrides such as arsine or pho~phlne are avoided.
Of part~cular usefulne~s are 6ilicon hydrides of the general formula Sin H2~2, such as SiH~, Si2H6 and Si6H~.
-6- 2~7~
However, other hydride~ ~uch as Ge2HS, Ge~20, SnH~, SnH6 or PbH~.
may be used.
In the above for~ula for cilicon hydrides, n is generally from 1 to about 10. However, n can be a higher value a~
silicon hydrides are known to exhibit catenation. See ~dvanced InLoraani ChemistrY, Cotton and Wilkin~on, Third Edition.
AB used hereln, the phrase "ga~eous hydrides in low concentration" generally means gaceous hydrides of a concentration of from about 10 ppb to about 10 ppm. More preferably, the concentration is about 50 ppb to about 5 pp~.
Most preferably, however, the concentration about 100 ppb to about 1 ppm.
In accordance w~th the present invention in order to pa3~ivate a ~etal surface to enhance the gtability of a ga~
~ixture containing gaseous hydrides in low concentration in contact therewith, it is first necessary to purge the gas or gas mixture initially in contact with the metal surface with inert gas to remove the purged ga As an inert purging gas, any gas which is generally chemically non-reactive may be used. For example, the so-called noble gases, such as krypton, xenon, helium, neon and argon may be used. However, other ga~es such ae hydrogen and nitroqen may be u~ed.
Generally, the inert purging ga~ will be passed over the metal surface for a ti~e and in an amount ~ufficient to re~ove ~ub~tantially all of the pury~d gas. Typlcally, the purging -7- 2~7~
gaR is pa~sed over the metal surface, or through à volume defined by a contlnuous metal surface, such as a compressed gas ~torage cylinder, for anywhere from ~everal ~econds to up to about 30 minutes at from 1 to about 3 atmosphere~ of pressure. However, higher pressures may be u~ed, if desired.
In accordance with the present invention, nitrogen ha3 been found to be advantageous as an inert purqing gas, although other inert gases may be used.
After purging the gas in contact with the metal surface, the metal ~urface 15 then exposed to an amount of passivating agent containing an effective amount of one or more gaseous hydride~ of silicon, germanium, tin or lead, and for a time sufficient to pas~ivate the metal surface.
Generally, the higher the concentratlon of passivating ~-?
agent used, such as silane, the shorter the exposure time required. However, passivating agent concentration~ of as low a~ 1 ppm may be used, or as high as 100%. For example, if a very low concentration of silane is used, exposure times in excess of 80 hours are usually required. Generally, exposure timee of about 100 hours are typically used for dilute passivating agents. However, if relatively pure passivating agent i~ used, for example, generally les~ than 60 minute~
exposure t~me i~ required, preferably less than 30 minutes.
A~ de~cribed above, the phrase "pure passivating agent"
means that the pasRivating agent used is the pure gaseou~
hydride of one or more ~illcon, germanium, tin or lead.
2~7~
While any concentration of passivating agent may be used, it is ganerally desirable to use a concentration in the range of about 0.01% to 20% by volume. It is preferred, however, to use a concentration in the range of about 0.01% to 5% by volume. With such concentrations, an exposure time of from about 1 to 24 hours i8 generally required. Generally, for larger metal ~urface~, such a~ vessels, larger volumes of passivating agent ~ay be used.
In accordance with the present invention, substantlally all of the purged ga~ is displaced or removed by the inert gas .
As used herein, the phrase "substantially all of the purged gas" means that the purged ga~ is removed to an extent of above 99% by volume.
Generally, the purged gas is air, however, other gases or gas mixtures, such as mixtures mainly containing nitrogen and oxygen, may be purged in accordance w~th the present invention.
Generally, the exposure of the metal surface to the passivating agent may be effected at from very low temperatures of about -20-C to up to right below the gaseous hydride decomposition temperature of the one or more gaseous hydrldes in the passivating agen~. For example, the decompo3ition temperature of ~llane is 250 C. However, it is generally preferable to effect the exposure at from about lO-C
to about lOO-C. It i~ more prefersble to effect the 9 2 ~ 7 ~
passivating agent expo~ure at from about 20-C to about 50-C.
However, it ls most advantageous to effect the expoeure at about 25-C.
Although the exposure may be effected at high temperature~, the gas phase reaction of the one or more ga~eoue hydride of the passivating agent, euch a~ silane, i8 preferably kept to a minimum to avoid the formation of particle~. Generally, this means at a temperature of less than the pa~sivating agent gaseoue hydride decomposition temperature.
After subjecting the metal surface to treatment with passivating agent, the latter is, itself, purged with an inert purging gas, such as nitrogen. However, the noble gase~ a~
described above may be used.
The present invention also provides an optional fourth step in wh~ch the metal surface is then exposed to an oxidizing gas in order to stabilize the adsorbed pas~ivating agent on the metal surface. As an oxidizing gaB ~ gaB mixtures containing nitrogen and oxygen may be used, for example.
Generally, oxidizing gas ~ixtures may b~ used which are capable of oxidizinq the adsorbed passivating agents to an inert oxidized form. For example, gas mixtures contalning from about 1 to 10% volume of oxygen in nitrcqen may be advantagesusly used when using such mixtures to oxidize the adsorbed passivating agent, metal surface exposure timee of fllm about 30 eec. to about 3 ~inutes are generally used.
-lO- 20701 ~
However, shorter or longer exposure time~ may be us2d as required.
In general, the oxidation step may be effected at the same temperatures as used for the passivation step, with temperatures of from about lO-C to about lOO C being preferred, and with temperaturQ~ of from 20-C to about 50-C
being most preferred.
In accordance with this a~pect of the pre~ent invention it has been discovered that adsorbed gaseous hydride may be desorbed very slowly over a period of time thus reducing the effectiveness of the passivation treatment over time. By oxidizing the adsorbed passivating agent containlng a gaseous hydride, such as silane, for example, an inert compound, such as sio2, may be formed. Hence, the oxidation ctep provides a means to stabilize the pa~slvated metal surface for long term use.
Figures 1 and 2 will now be described in more detail.
Flgure 1 provide~ a schematic flow diagram using mass flow controllers, an arsine permeation device, valves and port valves A and B in fluid connection. This apparatus is conveniently used to test the stability of gaseou~ hydrides, a~ measured by an inductively coupled plasma spectrophotometer. However, other detectlon means known to those skilled in the art may be used instead.
Figure 2 illustrates a summary of stability data from sample~ A, ~ and C a~ defined hereinbelow in the sxample. In -11- 2~7~ 3.~
particular, the 1 ppm treatment (sample C) failed to passivate the metal surface after 69 hour~ of exposure. Generally, at such low concentrations, in exces~ of 70 hour~ of exposure is required, preferably at least 80 hours of expo6ure.
The pure silane treatment (sample B) effected surface passivation in le~ than 30 mlnutes of exposure. Sample A iB
a controlled sample.
Generally, in accordance w~th the present invention, the ga~eous hydride treatment is effected to passivate 6ubstantially all of the metal surface. ~B u~ed herein, the term "~ubstantially all~ means that at lea~t 90% of the metal surface in contact with the gaseous hydride is passlvated.
However, it i~ preferred if at least 99% of the metal surface in contact with the gaseous hydride is passivated. It is particularly preferred if at least 99.9% of the metal surface in contact with the gaseou~ hydride is passivated.
The present invention will now be further illustrated by reference to certaln examples which are provided for purposes of illustration and are not intended to be limitative.
Example In order to demonstrate the effect of the present invention on ~etal surfaces, a 1/4" ID sta~nless steel tube was used.
Three identical ~amples (A, B and C) of 1/4" ID stainle~s ~teel tubing~ were exposed to amblent air under the ~ondit~on~
-12- 20701~
typical in the preparation of gas handling and storage eguipment. It is known that under such exposure condltlons, the stability of mixtures is very poor. All of the sample~
were then purged with dry N2 gas at room temperature. Sample A
~erved as a controlled sample. Sample B was then treated with flowing pure silane for 30 minutes at room temperature and sample C wa~ purged with 1 ppm silane for 72 hours, followed by purging with dry air, according to the condltions de~cribed below.
The 6tability of hydrides in the ~o prepared samples A, B
and C was tested in a setup as shown ~n Figure 1. The tube was filled with argon gas contalning 1 ppm arsine. This gas was kept in the tube by means of the valve 2 in Figure 1 for var~ oU8 periods of time. ~fter that, the gas was introduced into a device capable of meaguring the concentration of hydride remaining in the gas. In this example, the device is an inductively coupled plasma spectrophotometer. However, other detection means may be used. The ratio of initial fill concentration to final concentration was used to measure the gas stability. The results for a typical test with arsine are shown in Figure 2.
Additionally, the present lnventlon also provides storage mean~ for a gas or gas mixture, which means at least has an interior metal surface thereof which ha3 been passivated.
However, the 6torage means may be completely made of metal.
Preferably, the storage means ls co~pressed ga8 6torage -13- 2Q70~5 cylinder. However, the storage means may be a mobile storage means, such as a tank tractor traller rig or a railroad tank car.
Thus, the present invention provide~ storage means havlng at least an interior metal surface thereof which i6 passivated, thereby enhancing the stability of a gas mixture containing one or more gaseous hydrides in low concentratlon when in contact therewlth. As used herein, the term "passi~ated" means that the internal metal surface of the storage means has been sub~ected to the pre~ent passivation proce~s and i~ thus unable to react with gases or gas mixtures stored therein which contain low concentrations of gaseous hydrides. In accordance with the present inventlon, it is advantageous if the passivating agent used i8 a silicon hydride of the formula Sin H2~Z, wherein n ~g about 1-10, more preferably n is 1.
It is, however, particularly preferred if the passivated ~torage cylinder whose internal surface has been pas~ivated with ga6eous hydride passivating agent in accordance with the present proces~.
Having described the present invention, it will now be apparent to one of ordinary sklll ln the art that many changes and modlficatlon~ may be made to the above embodiments without departing from the 6pirit and the scope of the present invention.
Claims (14)
1. A process for passivating a metal surface to enhance the stability of a gas mixture containing one or more gaseous hydrides in low concentration in contact therewith, which comprises:
a) purging gas in contact with said metal surface with inert gas to remove said pursed gas, b) exposing the metal surface to an amount of a passivating agent comprising an effective amount of gaseous hydride of silicon, germanium, tin or lead, and for a time sufficient to passivate said metal surface, and c) purging said passivating agent using inert gas.
a) purging gas in contact with said metal surface with inert gas to remove said pursed gas, b) exposing the metal surface to an amount of a passivating agent comprising an effective amount of gaseous hydride of silicon, germanium, tin or lead, and for a time sufficient to passivate said metal surface, and c) purging said passivating agent using inert gas.
2. The process of Claim 1, wherein said metal surface comprises steel, iron or aluminum.
3. The process of Claim 1, wherein said metal surface is a compressed gas storage cylinder.
4. The process of Claim 1, wherein said purged gas is air.
5. The process of Claim 1, wherein said inert gas is nitrogen, argon, krypton, xenon or neon.
6. The process of Claim 1, which further comprises, after step c), exposing the metal surface to an oxidizing gas or gas mixture in an amount and for a time sufficient to stabilize the adsorbed passivating agent on the metal surface.
7. The process of Claim 1, wherein said one or more gaseous hydrides in low concentration are selected from the group consisting of phosphine, arsine and stibine.
8. The process of Claim 1, wherein said gaseous hydride passivating agent is selected from the group consisting of a silicon hydride of the formula Sin H2n+2, wherein n is 1 to about 10; Ge2H6, Ge9H20, SnH4, SnH6 and PbH4.
9. The process of Claim 8, wherein said gaseous hydride passivating agent is a silicon hydride of the formula SinH2n+2, wherein n is from 1 to about 10.
10. The process of Claim 9, wherein said silicon hydride is SiH4.
11. A storage means having at least an interior metal surface thereof which is passivated with a passivating agent comprising an effective amount of a gaseous hydride of silicon, germanium, tin or lead.
12. The storage means of Claim 11, which is a tank tractor trailer rig or a railroad rank car.
13. The storage means of Claim 11, which is a compressed gas storage cylinder.
14. The storage means of Claim 11, which comprises conduits, pipes or containers.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US70918391A | 1991-06-03 | 1991-06-03 | |
| US07/709,183 | 1991-06-03 | ||
| CN92109655A CN1039925C (en) | 1991-06-03 | 1992-08-21 | Process for passivating metal surfaces to enhance the stability of gaseous hydride mixtures at low concentration in contact therewith |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2070145A1 true CA2070145A1 (en) | 1992-12-04 |
Family
ID=36782323
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002070145A Abandoned CA2070145A1 (en) | 1991-06-03 | 1992-06-01 | Process for passivating metal surfaces to enhance the stability of gaseous hydride mixtures at low concentration in contact therewith |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0517576B1 (en) |
| JP (1) | JP3162480B2 (en) |
| KR (1) | KR100227064B1 (en) |
| CN (1) | CN1039925C (en) |
| CA (1) | CA2070145A1 (en) |
| DE (1) | DE69209149T2 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5479727A (en) * | 1994-10-25 | 1996-01-02 | Air Products And Chemicals, Inc. | Moisture removal and passivation of surfaces |
| CN105387337A (en) * | 2014-09-09 | 2016-03-09 | 中国石油天然气股份有限公司 | Aluminum alloy gas cylinder and treatment method thereof |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1975415B (en) * | 2002-05-29 | 2010-09-22 | 液体空气乔治洛德方法利用和研究的具有监督和管理委员会的有限公司 | Preparation method for article comprising an acid gas and a matrix gas |
| JP4609177B2 (en) | 2005-04-28 | 2011-01-12 | チッソ株式会社 | Method for extending luminescence time of calcium-binding photoprotein solution |
| EP2861779A1 (en) * | 2012-06-15 | 2015-04-22 | Praxair Technology Inc. | Cylinder preparation for maintaining stability of stored materials |
| US10767259B2 (en) | 2013-07-19 | 2020-09-08 | Agilent Technologies, Inc. | Components with an atomic layer deposition coating and methods of producing the same |
| US20150024152A1 (en) | 2013-07-19 | 2015-01-22 | Agilent Technologies, Inc. | Metal components with inert vapor phase coating on internal surfaces |
| CN107109644B (en) * | 2015-01-14 | 2020-11-06 | 安捷伦科技有限公司 | Component with atomic layer deposition coating and method of making the same |
| CN106185850B (en) * | 2016-07-15 | 2018-09-14 | 合肥正帆电子材料有限公司 | The passivation process of electron level arsenic hydride, hydrogen phosphide and its gas mixture steel cylinder |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1530337A (en) * | 1977-09-15 | 1978-10-25 | Central Electr Generat Board | Application of protective coatings to metal or metal with an oxide coating or to graphite |
| GB2107360B (en) * | 1981-10-12 | 1985-09-25 | Central Electr Generat Board | Depositing silicon on metal |
| US4714632A (en) * | 1985-12-11 | 1987-12-22 | Air Products And Chemicals, Inc. | Method of producing silicon diffusion coatings on metal articles |
| FR2633311A1 (en) * | 1988-06-24 | 1989-12-29 | Kodak Pathe | PROCESS FOR THE TREATMENT OF METAL PARTICLES AGAINST CORROSION AND PARTICLES OBTAINED |
| GB2530337B (en) * | 2014-09-22 | 2018-10-17 | Bae Systems Plc | Graphene Manufacture |
-
1992
- 1992-06-01 CA CA002070145A patent/CA2070145A1/en not_active Abandoned
- 1992-06-01 JP JP14071292A patent/JP3162480B2/en not_active Expired - Fee Related
- 1992-06-02 EP EP92401496A patent/EP0517576B1/en not_active Expired - Lifetime
- 1992-06-02 KR KR1019920009562A patent/KR100227064B1/en not_active IP Right Cessation
- 1992-06-02 DE DE69209149T patent/DE69209149T2/en not_active Expired - Fee Related
- 1992-08-21 CN CN92109655A patent/CN1039925C/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5479727A (en) * | 1994-10-25 | 1996-01-02 | Air Products And Chemicals, Inc. | Moisture removal and passivation of surfaces |
| EP0709635A1 (en) | 1994-10-25 | 1996-05-01 | Air Products And Chemicals, Inc. | Moisture removal and passivation of surfaces |
| CN105387337A (en) * | 2014-09-09 | 2016-03-09 | 中国石油天然气股份有限公司 | Aluminum alloy gas cylinder and treatment method thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH05214507A (en) | 1993-08-24 |
| CN1082623A (en) | 1994-02-23 |
| DE69209149T2 (en) | 1996-09-05 |
| DE69209149D1 (en) | 1996-04-25 |
| JP3162480B2 (en) | 2001-04-25 |
| KR100227064B1 (en) | 1999-10-15 |
| KR930000923A (en) | 1993-01-16 |
| EP0517576B1 (en) | 1996-03-20 |
| CN1039925C (en) | 1998-09-23 |
| EP0517576A1 (en) | 1992-12-09 |
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