US 2159124 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
Patented May 23, 1939 UNITED STATES PATENT OFFICE ALLOY tion of New Jersey No Drawing. Application May 20, 1937, Serial No. 143,756
This invention relates to lead alloys and provides certain alloys of calcium, lead and tin which have been found to possess properties making them of particular importance in the manufacture of battery grids and sheathing for electrical conductor cables.
The alloys of the invention consist of 0.01% to 0.1% calcium, 0.35% to 1.75% tin and the balance lead, it being understood that the alloys, while essentially ternary compositions, may contain minor impurities within the scope of the invention as defined in the appended claims.
The alloys may be readily compounded in any of several manners, one of the simplest being to melt the lead in an ordinary cast iron kettle and stir in the requisite tin and calcium, the latter being added in the form of a calcium-lead alloy.
The advantages accompanying the use of the n alloys of the invention in the manufacture of such products as battery grids and cable sheathing are readily apparent from a consideration of the properties of the new alloys.
Thus, the alloys of the invention are eminently more stable upon remelting than are the calciumlead alloys recently advocated for battery grids as a substitute for antimonial grid metal. This is well illustrated from the following tabulated results of drossing tests conducted on several of the new alloys by melting 1000 grams of the 30 alloy in a special machine equipped with a revolving paddle which swept the surface of the molten metal (350 (Li-360 C.) at exactly 100 R. P. M. for 30 minutes after which the remaining metal was skimmed clean, cast and chemi- 5 cally analyzed. A typical result from a like test on a binary calcium-lead alloy is included for the purpose of comparison.
The ability of the calcium-lead-tin alloys-of the invention to retain a much larger percentage of their calcium upon remelting than is the case 50 whenremelting binary calcium-lead alloys is of considerable importance when one considers the large amounts of metal that must be remelted in many processes as, for-example, in manufacturing battery grids where the weight of metal 55 to be remelted and returned to the process often approximates the weight of satisfactory grids produced. Hence, it will be appreciated that while calcium-lead alloy grids may be considered to constitute an improvement over antimonial grids in that they are said not to accelerate sulphation or cause self-discharge of the battery, the calcium-lead-tin alloys of the invention are a decided improvement over the calcium-lead grids in that they are vastly more stable upon remelting and in this respect more closely approach antimonial grid metal which may be repeatedly remelted with very little change in chemical composition.
In addition to the marked increase in stability of the calcium-lead-tin alloys of the invention over alloys of calcium-lead, the presence of the tin has been found to impart increased tensile strength. Thus a cast alloy consisting of 0.054% calcium, 1% tin and the balance lead exhibited a tensile strength of approximately 8000 lbs/sq. in. as compared to 5500 lbs/sq. in. for a cast alloy consisting of 0.057% calcium and the balance lead. Apparently, the tin exerts a strengthening effect by stiflening the matrix. On extruded material, .tensile strength values of about 6500 lbs/sq. in; were obtained for the calciumlead-tin alloy but because of the technique employed in the tests this figure should not be considered as representing the maximum obtainable. Fatigue strength was found to be approximately 1700 lbs/sq. in. for 20 million cycles at 2000 R. P. M.
It will thus be apparent to those skilled in the art that the characteristics of the improved alloys fit them for such special uses as cable sheathing and battery grids. In connection with the latter use it may be pointed out that the new alloys retain their hardness upon remelting and lend them elves to grid manufacture by punching or sta'm ing methods which some manufacturers have long felt to be desirable but to which antimonial lead is not easily adapted by reason of the fact that while it can be rolled into sheet material, the sheets are softer and less rigid than the cast metal and the normally rolled sheet actually softens with time unless the tendency be overcome by heat treatment thereby making the process commercially unattractive.
While the beneficial properties which characterize the improved alloys of the invention are exhibited, to a more or less degree, by any composition falling within the limits hereinbefore specified (0.01% to 0.1% Ca, 0.35% to 1.75% Sn, balance Pb). it has been found that a tin range of between 0.5% and 1.25% is preferable for most uses.
What is claimed is:
1. An alloy consisting of 0.01% to 0.1% calcium. 0.35% to 1.75% tin, and the balance lead.
2. An alloy consisting of 0.01% to 0.1% calcium. 0.5% to 1.25% tin, and the balance lead.-
mass 0. nrrrrnamn. ALBERT J. PHILLIPS.
, ALBERT A. sum, J.