JPS63206473A - Treatment device for depositing tungsten carbide layer - Google Patents

Abstract

PURPOSE:To prevent deposition of tungsten carbide on the parts to be exposed to a reactive gas in a reaction furnace by previously forming a fluoroplastic film on the surfaces of said parts. CONSTITUTION:The fluoroplastic film is previously formed on the surface of the parts (inside wall surface of the reaction furnace, mounting jigs, etc.) to be exposed in the reactive gas in the furnace into which a metallic base material is charged in the device for depositing the tungsten carbide layer on the metallic base material. Formation of the fluoroplastic film is executed by first degreasing and cleaning the surfaces of the parts where the deposition is not required, then diluting a tetrafluoroethylene resin with a solvent to adjust the viscosity and coating the same by an air spraying method at an ordinary temp. to the parts. The coating is then dried for about 30min at about 90-100 deg.C to evaporate the solvent. The parts are thereafter held for about 10-15min at about 350 deg.C to form the fluoroplastic film to about 20-30mu thickness on the parts. The deposition of the tungsten carbide on the parts is thereby prevented and the corrosion resistant to gaseous HF is imparted to the parts.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a processing apparatus for depositing a tungsten carbide layer.

(Prior art) The technology of depositing a tungsten carbide layer on the surface of metal parts by CVD (chemical vapor deposition) method to obtain wear resistance is well known. For example, JP-A-52-89583
In the publication, a nickel phosphorus plating layer is formed on the surface of a steel base material, and a tungsten carbide layer is deposited on the nickel phosphorus plating layer, thereby improving the adhesion of the tungsten carbide layer to the steel base material. There are descriptions of techniques that can improve In this case, the tungsten carbide layer is formed using a gas phase reaction between WF6, hydrocarbon gas, and hydrogen.

(Problems to be Solved by the Invention) By the way, in depositing the above tungsten carbide layer, the metal base material is charged into a reactor using a mounting jig and the above gas phase reaction is carried out. However, there is a problem in that tungsten carbide is deposited not only on the metal base material but also on the inner wall surface of the reactor, the above-mentioned mounting jig, etc. That is, there is a problem that the reaction gas is wasted due to the precipitation in unnecessary parts, and that it takes time and effort to remove the precipitated tungsten carbide.

(Means for Solving the Problems) The present invention, as a means to solve the above problems, forms a fluororesin coating on the surfaces of parts exposed to reaction gas in a reactor into which metal substrates are charged. A processing apparatus for depositing a tungsten carbide layer is provided.

As the fluororesin, PTFE (tetrafluoroethylene 4
1), PFA (tetrafluoroethylene-perfluoroalkoxyethylene copolymer), FEP (tetrafluoroethylene-hexafluoropropylene copolymer), etc. can be used. In addition, the formation of the fluororesin film can be done by brushing the fluororesin liquefied using a solvent, air spraying,
This can be done by applying it to the surface of the above-mentioned parts using an electrostatic coating method or the like, drying and baking (180 to 400''C).

(Function) In the above processing apparatus, tungsten carbide is difficult to react and precipitate on the fluororesin coating, and will be deposited on the surface of the metal base material on which the fluororesin coating is not formed. Further, when tungsten carbide is deposited by a gas phase reaction, HF gas is generated as exhaust gas, but the fluororesin coating has corrosion resistance to this HF gas and is not attacked.

(Effects of the Invention) Therefore, according to the present invention, by forming a fluororesin film, it is possible to prevent tungsten carbide from being deposited on parts in the reactor where precipitation is unnecessary.

The trouble of removing unnecessary tungsten carbide can be saved, and the waste of reaction gas can be prevented.Furthermore, the fluororesin coating is not attacked by HF gas, so the above-mentioned tungsten carbide precipitation prevention effect can be maintained for a long period of time. is obtained.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

In the tungsten carbide precipitation treatment apparatus (low-temperature CVD apparatus) shown in Fig. 1, 1 is a reactor into which the metal base material W on which tungsten carbide is to be deposited is charged, 2 is a reaction gas supply system, and 3 is a gas exhaust system. , 4 is a suction system for reducing pressure.

In the reactor 1, a retort body 6 is housed in a heat insulating container 5, and a cover 7 of the retort body 6 is covered with a metal base material W.
A mounting jig 8, a gas supply pipe 9, a gas discharge pipe 1O1, a suction pipe 11, and a pressure gauge 28 are attached. Further, an induction coil 12 for heating is provided on the inner circumference of the heat insulating container 5. The mounting jig 8 is formed by providing a supporting plate on a support plate from which the metal base material W is suspended. The gas supply pipe 9 is provided in a spiral shape around the mounting jig 8, and its tip is closed with a blind stopper 13.

Therefore, the retort main body 6, cover 7, and mounting jig 8
．． The gas supply pipe 9, the gas discharge pipe 10, the suction pipe 11, and the pressure detection pipe of the pressure gauge 28 are all made of metal,
The inner peripheral surfaces of the retort body 6 and the cover 7, the mounting jig 8
The parts exposed to the reaction gas in the reactor 1 are covered with a fluororesin film. The thickness of this fluororesin coating is about 20 to 30 μm.

In the reaction gas supply system 2, a WFI (tungsten hexafluoride) supply source 1 is connected to the gas supply pipe 9 of the reactor 1.
5 is a valve 16, a pump 17, a heater 18, a valve 19
, a mass regulator 20, and a mixer 21 are connected in this order from the upstream side. Then, for the mixer 21, c
II Hl (benzene) source 22 and H2 (hydrogen)
Supply g23 is connected to valves 24, 25 and mass regulator 2, respectively.
6. An Ar (argon) supply source 29 is connected to the heater 18 and the Cs Hm supply source 2 through a flow meter 27.
2 for valve 30.31 and flow meter 32.33 respectively
connected via.

A water ring pump 34 and a gas purifier 35 for removing HF gas are interposed in the gas exhaust pipe 10 of the exhaust gas exhaust system 3. Further, a vacuum pump 36 is interposed in the suction pipe 11 of the suction system 4.

FIG. 2 shows the surface structure of the parts exposed to the reaction gas in the reactor 1. That is, in the same figure,
40 is a metal base material (II or other ferrous metal or non-ferrous metal), and 41 is a fluororesin coating. This fluororesin coating 41 is formed as follows.

First, the surface of the metal base material 40 is degreased and cleaned. Tetrafluoroethylene resin (Polyflon TFE Tough Coat Enamel TC-7800 manufactured by Daikin Industries, Ltd.) was diluted with a solvent (thinner) to adjust the viscosity, and then sprayed onto the metal base material 40 at room temperature using an air spray method. Apply. Next, the solvent is evaporated by performing a drying process at 90 to 100°C for 30 minutes, and the coating film is baked by holding at 350°C for 10 to 15 minutes.
Get 1.

When using the above precipitation treatment apparatus, first, attach the metal base material W with a nickel phosphorus plating layer formed on the surface to the mounting jig 8.
and housed in the retort main body 6. Then, the pressure inside the retort body 6 is reduced to about 100 torr using the vacuum pump 36, and electricity is applied to the induction coil 12 to heat the metal base material W to about 350°C.

Next, open valves 16, 19, 25, and 30, and pump 1
7 supplies WFs gas, Ar gas, and H2 gas at a predetermined molar ratio into the retort body 6 little by little, while the water ring pump 34 operates to supply the gas in the retort body 6 with the vacuum pump 36 stopped. is discharged little by little. As a result, a tungsten layer is formed on the metal base material W through the following reaction.

WF,, +3H2-) V+68F Next, open the valves 24 and 31 and add WF, at a predetermined molar ratio.
Gas, Ar gas, C, H, gas, and H2 gas are supplied into the retort body 6 little by little, while the gas in the retort body 6 is discharged little by little as in the previous case. This results in
A tungsten carbide layer is formed on the surface of the tungsten layer of the metal base material W.

611! Fg+C*Hs+15Hz-) 61C+3
6HF1211Fs + Cabs +3382 →6
fC+ 72HF18WFs+CaHs +51H2→
By using 6W3C+108HF or more, a wear-resistant article in which a tungsten layer and a tungsten carbide layer are sequentially deposited and formed on the surface of the nickel phosphorous plating layer of the metal base material W can be obtained.

Therefore, in the precipitation reaction, the fluororesin coating 41 is formed on the articles exposed to the reaction gas in the reactor 1, such as the inner surface of the retort body 6, the cover 7, and the surface of the mounting jig 8, except for the metal base material W. Therefore, there is no precipitation of tungsten or tungsten carbide, and there is no corrosion caused by HF gas.

FIG. 3 shows a nickel phosphorus plating layer 43 on the surface of a steel material 42.
A fluororesin coating was partially formed on the test piece, and tungsten carbide was precipitated using the reactor 1 described above. This is what is shown. The conditions for this precipitation treatment are the same as in the above embodiment. In the figure, the entire white part on the upper side is the tungsten carbide layer 44, and the lower part shown in black with a white line pattern is the fluororesin coating 41. No precipitation of bite is observed.

Furthermore, FIG. 4 is an optical microscope photograph (400x) showing a cross section of the fluororesin coating 41 formed portion after the tungsten carbide precipitation treatment of the test piece. No precipitation was observed.

In addition, in the above example, a fluororesin coating was formed on all the parts exposed to the reaction gas in the reactor 1 (excluding the metal base material that is the object to be treated), but the fluororesin coating was formed only on some parts. Of course you can.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and Fig. 1 is a block diagram of a processing device, Fig. 2 is a cross-sectional view of the surface layer of a part on which a fluororesin coating has been formed, and Fig. 3 is a diagram showing the metallographic structure of the surface of a test piece. The micrograph shown in FIG. 4 is a micrograph showing the metal structure of the cross section of the portion of the test piece where the fluororesin coating is formed.

Claims (1)

[Claims] (1) In an apparatus for depositing a tungsten carbide layer on a metal base material by a gas phase reaction, a fluororesin coating is formed on the surfaces of parts exposed to reaction gas in a reactor into which the metal base material is charged. A processing device for depositing a tungsten carbide layer, characterized by: