US2129844A - Method of making bearing and gasket material - Google Patents

Description

Patented Sept. 13,1938 I METHOD OF MAKING BEARING AND GAS- KET MATERIAL Edwin F. Kiei'er, Cleveland, Ohio, assignor, by

mesne assignments, to Union Carbide and Carbon Corporation, a corporation of New, York No Drawing. Application July 21, 1934, I Serial No. 736,344

, '7 Claims.

This invention relates to a method of making porous structures and especially impregnated po- 'rous structures suitable for use as gaskets, bearings, or the like.

An object of this invention is to provide a hard, porous base or matrix which is capable of being impregnated with softer materials. Another object of this invention is to provide a method of producing a base or matrix having a largev number of fine pores. Still another objectis to provide a, hearing or gasket of porous copper im-' pregnated with softer materials. The above and other objects together with the novel features of this invention will be apparent from the following description.

To achieve the above-enumerated objects in accordance with this invention, a matrix is first prepared from a suitable metal or its oxide. Any oxide of ametal may be used which is capable of being reduced and at the same time of being formed into a coherent mass in the manner of a porous honeycombed structure. However, it is preferred to employ copper and/or copper oxide in forming a matrix because of inherent characteristics peculiar to this metal. Desirable results are obtained with a comminutedmixture of copper and copper oxide, but copper or copper oxide alone is also suitable. The copper and copper oxide may be finely divided or pulverized and intimately mixed with a suitable reducing agent. Ammonium chloride provides the necessary chemical constituents to perform the reducing reaction and also acts as a binder to cause the copper and copper oxide particles to adhere closely together. The limiting proportions of NHsCl are to 18% but I prefer to use from 4' to 15%. Above-18% there is a decided tendency for the formed article to crack and deform. Below 4% reaction will occur most speedily and efliciently."

An inert atmosphere, from which oxygen has been excluded, materially aids in making the reaction complete, and it has also been found that an increase in pressure above atmospheric will tend to assist in speeding the baking process. The baking acts to sinter the molded sheets of well Considerable ammonium chloride is volatilized and does not enter the reaction. However, the volatilized ammonium chloride serves as a,blow- 'ing'agent to produce porosity as well as to prevent oxidation. This results in the sheets or molded material becoming honeycombed or filled with pores. The copper particles become fused together at intermediate points throughout the mass and. form a substantially rigid foraminous matrix which is not subject to crumbling nor to crushing under moderate pressure.

When the sheets have cooled, they are suitable for use as gaskets in their then existing form. However, superior gaskets may be made by impregnating the porous matrices with gums, resins, or waxes, or with softer metals such as tin or lead.

I have found that lead and lead-tin alloys are well adapted for this impregnation. This is best applied by soaking the porous matrix in molten lead or lead-tin alloy. The amount of lead taken up may vary from 6% for copper having a low porosity to as high as 105% for copper having a higher porosity. When resins 'or the like are used as impregnating material, the percentage will be much lower. Other suitable materials may be used for impregnation, such as rubber, vinyl polymers, phenol formaldehyde condensation products, and the like. In nearly all instances I prefer to use the largest amount of impregnating material that the foraminousmatrix will take up; that is, the foraminous matrix is preferablysubstantially saturated with the impregnating material. In most cases immersion in the molten material is suflicient. However, if the introduction of more material is required, or if the material is viscous and does not penetrate with ordinary soaking, pressure methods can be resorted to.

A matrix of copper which has been prepared in accordance with this invention and impregnated with lead or tin or alloys of soft metals is admirably suited to. serve as a. bearing material. The relatively hard structure of-the matrix withstands the high pressures which are experienced in the contact of metal parts movable in relation to other and cooperating parts. The softer impregnated material servesas an antifriction stance tends to iiow to the surface of the sheet and prevents leaks from occurring ,in glands, stufiing boxes, and between metal edges, as in engine blocks and tank covers. a

Although a preferred method and resulting gasket and bearing materials have been described, it will be understood that changes may be made without departing from the principles or scope of this invention.

I claim:

1. A method of making a porous structure comprising the steps of mixing an unalloyed finely divided oxide of copper with an ammoniacal salt; molding the mixture to a desired shape; and sintering the molded ingredients to form a porous mass of substantially pure copper.

2. A method of making a. porous structure comprising the steps of mixing comminuted copper and copper oxide with ammonium chloride; molding the mixture to a desired shape; and heating the molded ingredients tocreate a coherent porous material.

3. A method of making an impregnated bearing comprising the steps of mixing an unalloyed pulverulent oxide of copper with ammonium chloride; molding the mixture; heating the molded ingredients to form a porous structure of substantially pure copper; and introducing a softer metal into the pores.

d. A method of making an impregnated gasket comprising the steps of mixing unalloyed pulverulent copper with ammonium chloride; molding the mixture; heating the molded ingredients to form a porous structure of substantially pure copper; and introducing an alloy of lead and tin into the pores.

5. A method of making an impregnated material suitable for use as gaskets, hearings or the like, comprising, the step of mixing comminuted copper and copper oxide with 4 to 18% ammonium chloride; molding the mixture; heating the molded ingredientsin a reducing atmosphere to form a foraminous structure; and introducing a softer substance into the pores.

6. A methodof making an impregnated material comprising the steps of mixing an unalloyed pulverulent oxide of copper with a combined blowing and reducing agent; molding the mixture; heating the molded ingredients in a reducing atmosphere to produce a sintered structure of substantially pure copper; and introducing from 6 to 105%. by weight of an alloy predominantly lead into the pores.

7. A method of making an impregnated material comprising the steps of mixing a pulverulent oxide of copper with ammonium chloride; molding the mixture; heating the molded article in a reducing atmosphere to form a porous structure; and introducing a lead-tin alloy into the pores.