248 



SCIENCE. 



[N. S. Vol. IX. No. 216. 



The purpose of the investigation was 

 largely that of finding a way of applying to 

 alloys for bearings the tests previously de- 

 duced respecting relations of fusibility and 

 other properties. General experience has 

 shown that white alloys, customarily used 

 for bearings in machinery, are much less 

 frequently overheated than those made, as 

 previously common, of bronze, while they 

 are found also to reduce friction something 

 like 20 per cent. In some instances the 

 reported accidents with the two classes of 

 metal are but 2h with the white metal as 

 compared with 100 with the yellow in ordi- 

 nary railroad work. Their wear is also but 

 about 0.4 that of the bronze. So long, how- 

 ever, as a layer of oil remains in eifective 

 depth, on the rubbing surface, the coeffi- 

 cient of friction is substantially the same 

 with all bearing metals. Flooded journals 

 give immunity from friction, safety from 

 heating and wear, and independence of the 

 nature of the rubbing metals, except so far 

 as their conductivity affects the removal of 

 heat developed by friction. 



Charpy gives an extensive table of the 

 composition of various anti-friction alloys 

 as reported by the authorities, including 

 substantially all those reported by Dudley, 

 Ledebur and Thurston. His own investi- 

 gations are upon alloys of lead and anti- 

 mony; of lead, tin and bismuth; of tin, cop- 

 per and antimony; of lead, copper and an- 

 timony; of zinc, tin and antimony, and of 

 copper, tin and lead ; all of which are 

 studied under compression and wear, and 

 micrographically. Admirable prints are 

 given of the micrographic development, 

 and the ' stress-strain ' diagrams, both for 

 the binary and ternary alloys, are exhibited; 

 the writer using the Thurston 'tri-axial' dia- 

 gram, and the corresponding 'glyptic ' rep- 

 resentation in the solid, to illustrate his 

 work.* The paper abounds in most inter- 



* See Transactions Am. Soc. Meet. Engrs., No. 

 DCCLXXVII., Vol. XIX., 1898. Sauveur, in this 



esting and helpful illustrations of these 

 kinds. 



He concludes substantially as follows : 



(1) All these alloys, when fitted for use 

 as anti-friction metal, exhibit the same 

 general characteristics. They are made up 

 of hard particles set in a soft and plastic 

 alloy. The load is taken by the hard metal, 

 while the friction is reduced by the com- 

 paratively low coefiicient of friction and by 

 the power which is given by the soft alloy 

 of adapting the loaded surface to the posi- 

 tion of the journal and to its deformations. 

 The ternary alloys are thought better than 

 the binary. 



(2) The limits of practically useful al- 

 loys and mixtures are determined by this 

 method of investigation and the best com- 

 positions are identified. 



(3) The processes adopted are mainly 

 grapliic and micrographic, to ascertain 

 whether the quality is suitable and the 

 composition such as has been found de- 

 sirable, and compressive tests to ascertain 

 whether it has the needed power of resist- 

 ing pressure, without serious deformation 

 under ordinary conditions of use. ' Cooling 

 curves ' were found very helpful. 



(4) Alloys of lead and antimony should 

 contain between 15 and 25 per cent, anti- 

 mony. Those containing more of this con- 

 stituent are too hard and those containing 

 more lead are too soft ; the one will lead to 

 brittleness and fracture, the other to crush- 

 ing and cutting. 



(5) The copper-tin-antimony alloy of 

 best proportions is considered to be that 

 containing Cu. 5.55 ; Sn. 83.33 and Sb. 11.11 

 by weight. It is strong and tough, cor- 

 responding with the alloys empirically se- 

 lected for railroad journals by some railway 

 authorities. 



(6) The lead-tin-antimony alloys should 

 contain between 15 and 90 per cent, tin, and 



country, has most extensively employed these meth- 

 ods of micrography in the work of his laboratory. 



