US2228235A - Hardened base metal pen nib - Google Patents

Description

Jan 7, 1941- c. PFANsTlEHL 2,228,235

HARDENED BASE METAL PEN NIBr Filed March 28, 1940 Patented Jan. 7, 19,41

UNITED -sTATEs PATENT OFFICE l 2,228,235

nAnDENEn Basnmnmr. PEN Nm carirfansueh1,nigmana Park, m, assignor to Pfanstiehl Chemical Company, a corporation of Illinois Application March 2s, 194e, serial No. 326,519 1s claims.' (C1. 12o-109) This invention relates .to a hardened base metal pen nib and a method of producing it, and more particularly to a ferrous metal pen nib upon which is integrally formed a hardened integral '152, issued June 25, 1935. The pen mbe described' in Patent 2,053,406, issued September 8, 1936, were preferably ferrous base materials, for example, steel. In my Patent 2,154,181, issued April 11, 1939, the use of a stainless steel pen nib of the austenitic 18-8 type is described. The pens described in these patents are considerable improvements upon pens of similar type theretofore known. However, they do not have the wear resistance of pen points formed in the usual way by welding a so called Iridium tip to a steel base. By means of the present invention, ferrous base integral nibs are-hardened to produce a pen point which will have wear and corrosion resistance comparable with andhin many instances, actually better than those heretofore produced.

The invention is preferably carried out by adding to a base metal pen nib a hard, corrosion re- '30 sistant base metal tip. Preferably the tip is produced in situ by alloying with the tip portion of y the base a small amount of a hardening alloy.

The preferred hardening material is a' mixture of chromium carbide and cobalt which has been au assembled in the form of a minute pre-formedobject, for example, in the form of a disc, cube or a rough sphere. This metallic hardening chemical,-which itself is porous, soft, easily breakable and utterly unfit for pen point purposes, is pref- 40 erablyA tacked to the pen nib, for example, as `described in my Patent 2,005,752, or else by a light resistance weld, and, then the integral nib is formed in the usual manner.

preparing'it overcomes certainv dimcultieswhich' are found in other methods of procedure. I As an example of the invention, chromium caru bide was prepared by thoroughly mixing together The hardening, chemical is thoroughly melted and absorbed by chromium and carbon in proportions to form ber at about atmospheric pressure and the tem- 15 perature raised to 2700 F. and held there in the presence of the hydrogen for about an hour. In this process the materials combine to form CraCz which is. removed from the furnace after cooling. 'Ihe temperature used is low enough so that the material will readily pulverize. If the temperature is raised much above 27Q0 F., or if the heating is carried on too long, the mass begins to sinter and it is difilcult to pulverize properly. Under the .conditions the mass is only slightly \sintered and can readily be ground in a mortar or ball mill to produce particles of 150 mesh or less.

, The ypowdered chromium carbide so produced is then mixed with about 10% of cobaltic oxide (c0203) and 90% of chromium carbide, and cov- 3 ered with benZol or. some other protective, inert, thin liquid and is ball milled for approximately The mixed powders are thendried and again sifted through 150 mesh and pressed into minute granules in the shape of cubes or tiny at disc's, or any other convenient shape. 'I'his present operation should be carried out in a plastic die such as is described in`my Patents 2,169,280 andv 2,169,281, issued August 15, 1,939. The amount l of pressure employed is simply 40 .enough to hold the pressed material rmly in the desired shape. Usually 40` to 70 tons per square inchjis sufficient, and in some cases lower pressures can be used. The pressed cubes or discs are 'then placed in a. crucible-a large number may A b e placed in a single crucible-and heated to a bright red. heat between 1500, and 1900 F. for a few minutes in hydrogen. The length of heating is such that the cubes will not stick together. In Athe treatment, the cobaltic oxide is reduced bythe hydrogen to cobalt, which binds the small objects morev strongly together."4 It also "leaves them somewhat porous. The material, however,

in this condition is utterly unfit for use asa pen point. After forming, the granules are prefercondenser discharge tacking method describedy in Patent 2,005,752, or preferably by a light re,n

- sistance weld. Preferably the amount of coritact' is kept at a minimum, as shown in the draw'- ing, by tacking a corner of the granuletoy the nib. The blank with the hardening member so attached is then. placed in a suitable apparatus for forming integral nibs, for example, as described in Patents 2,005,752 and 2,053,406. In this apparatus the hardening member and the vnib are heated by an electric arc so that the hardening member and a portion of the steel are melted together to form a spheroidal tip. The chromium carbide disappears in the process, there being no clear line of division between the steel and any chromium carbide-cobalt alloy. Nevertheless, the tip of the pen is madel extremely hard and Qcompletely corrosion resistant by this process. The tip formed resembles precisely an integrally formed tip. In composition it varies from about 80% or` more of the chromium carbide alloy at the writing surface, to 40% or less at the part of the ball point nearest the bodyl of the nib.

The product is illustrated diagrammatically in the drawing in which Fig. 1 represents a stainless' steel pen blank lllhaving a tip portion Il; Fig. 2 represents a. perspectiveview of a small hardening cube i2; Fig. 3 is a view of the stainless steel pen nib blank I0 having the cube I2 lightly tacked toits tip Il; and Fig. 4 shows the pen blank I0 after the formation of the spheroid I3 by the fusion operation and after splitting the pen as indicated at I6.

The selection of a material for hardening presents some diiiiculties because hardening alloys tend to produce blow holes and do not produce generally dense close-grained'hard tip structure, or have the necessary resistance to corrosion.

The cobaltic yoxide is used in combination with the chromium carbide in preference to, the use of pure cobalt, because for some reason the mixture of chromium carbide and cobaltic oxide presses far better 'and produces a .better Vpreformed hardening member ythan a mixture of chromium carbide and cobalt. The amount of cobaltic oxide should be between 5% Vand 20% of the chromium carbide. AThe hardening members are small in comparison to the size of the tip produced. For tips of ordinary size. the

hardening member in the form of a rough cube 0.025 inchl on a side is satisfactory.

Theinvention may be practiced in a less satisfactory manner by pre-forming tipping granuls of the chromium carbide-cobalt material in combination with a suitable amount of stainless steel. For example, a tip may be pre-formed in any suitable size by forming in any .suitable manner a combination of the chromium carbide-cobalt alloy and stainless steel, the proportion of the stainless steel in the alloy being from 20% to `60%. This granule may then be welded to th pen nib in any satisfactory manner." .The -Ifreferredformof the invention, however, is much more economical to practice, and furthermore provides a gradation of4 alloy within the tip which is not readily procurable in-any other manner.

`Instead of or in. combination with the chromium carbide other refractory carbides compat- A`v\ 7riting surface.

bide or tungsten carbide or small amounts of it may be replaced with boron carbide. i

Cobalt may be replaced inwhole or in part by nickel or by` iron. When using either of these metals, however, the tendency thereof to form carbides must be considered and if appreciable amounts of either are used it may be necessary to supply a slight excess of carbon tofprevent the formation of an unsatisfied chromium carbide. rvlz "i The foregoing detailed description has been given for clearness oi understanding only, and no unnecessary limitations should be understood therefrom.

What I-claim as new, and desire to secure` b Letters Patent, is:

1. A stainless steel pen nib of the lit-8 type having integrally formed at the tip thereof a writing spheroid formed by fusion, said spheroid including a hardening metalnot present'in the body of thenib, said spheroidal writing surface being dense and close-grained. l

2. The method of forming a pen point from ferrous metals comprising fusing the point of a ferrous pen nib while in contact with a granule of hardening metal, whereby' an integral spheroidal writing surface vembodying the materialin the body of hardening metal is produced.

3. As av composition of matter, 'a formed minute body consisting essentially of a refractory l which lthe chromium carbide is essentially CrsCz A and the amount of cobalt is from '5%l to 20% of the total.

6. A composition as set forth im claim 4, in which the chromium carbide is essentially CraCz and the amount'of cobalt is approximately 10% of .the total.

7. As a hardening memberl for pen nibs, a minute, pressed, slightly porous body con g approximately 80% to 95% CraC: and 5% to 20% Co, .the Co having a distribution produced by reduction of a mixture of powderedncz and C0203' in intimate pressed contact by heated hydrogen.

8. As a composition of matter, a formed minute body consisting essentially of an alloy of chromium carbide and cobalt. f' chromium carbide being in the form of CnC: and representing from 80% to 95% of the total chromium carbide plus cobalt, together with an essentially fenous metal, the ferrous metal representing from 20% to 60% of the total.

9. A pen nib having a. body of austeni-tic 18-8 type stainless steel and having at the tip thereof a writing surface formed by fusion, said surface beingsubstantially more corrosion resistant to ink than the body of the nib and consisting essentially of metal ofthe body of the nib alloyed with chromium carbide, Ythe proportion of chromium carbide at .the writing surface being in the order of 80% and diminishing repidly away from the 1o. A stainless steel object comprising a'. body of austenitlc 18-8 type Stainless 'steel having integrally formed -th'ereon by fusion ofy a portion of the body a minute tip containing a hardening 4 alloying metal consisting essentially of chromium carbide with a small amount of cobalt.

11. A stainless steel object comprising a body of austenitic 18-8 type stainless steel having integrally formed thereon by fusion of a portionr freezing the molten metal into a small sphere, whereby an integral spheroidal writing surface embodying the material in the body of hardening metal is produced;

13. A pen including a metal nib having a tip integrally formed thereon by fusion of a portion of the nib, said integral tip having atom-ically distributed therein hardening meta-l, the concentration of hardening metal being greatest at the Writing surface of .the tip and diminishing rapidly and steadily with distance therefrom, the tip being markedly harder and more corrosion resistant than the nib because of the presence of the atomically distributed material, there being no nucleus of the hardening metal and there being nib metal at all parts of the tip.

CARL PFANSIIEHL.

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