INDUSTRIAL -4&\-D ELVGISEERIiVGCHEXISTRY
Mag, 1925
6-Garner, “The Carbonization of Lubricating Oils in Internal Combustion Engines,” J . Inst. Pelroleum Tech., 7, 98 (1921). 7--“Centrifugal Oil Cleaner,” Oil News, 9, No. 4, 21 (1921). &-Parish, “Dilution of Crank-Case Oil,” J . SOC.Automotive Eng., 8,
No. 3, 231, 254 g-Parish,
(1921).
“Reclamation
‘485
14-Clayden. “Effect of Dilution upon Viscosity and Oiliness of Lubric a n t , ” I t i d . . 47, 1023 (1922). l S F e n n o , “Reclamation of Used Motor Oil,” Sci. Lubrication, 1, 11 (1921). 16-”The Dilution of Lubricating Oil,” Motor Transport ( L o n d o n ) , 36,
of Used Motor Oils,” 5 . ’ .
of c r a n k - Case o i l 1 s Serious Factor Even in lO-Parish, “Crank-Case Oil Dilution Probl Summer,” .414tom0LiwL-f;~,,49, 415 (192?,,). m and I t s Solution,” Eng. tvorld, 20, 307 (1922). 1s-Knoch, CrosL., blathews, “Determination of Dilution of 11-Larson, “Dilution of Crank-Case Oil,” Sci. L U L. Crank-Case Oil,” I n d . Eng. Chem., 16, 1153 (1924). .cation, 1, No 10, 13 (1921). 1 G P a r i s h . “New Plan Regenerates Motor Oil Continuously as Auto12-Parish, “The Dilution of Lubricating Oil i* . I the Present AutomOtive Engine,” I b i d . , 2, No. 1, 5, 21 (1922). 13-“Reconditioning of Crank-Case Lul , I--.. re+Tk.i;> .4u(omo(r’ae I d . , 46, 910 (19221.
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Normal Sand-cast Alloys of Aluminium Containing Small Amounts of Silicon‘ By Samuel Daniels W I R DEPARTMEST, AIR SERVICE, XICCOOKF;EL.D, DLYTOY O ,H ~ U
1LICOS is found in metallic aluminium as one of the erately highly stressed party: the 4 copper-3 silicon a!luy principal impurities. Virgin aluminium ingot pro- having an ultimate strength of about 20,000 pounds per duced by electrolytic reduction is furnished to U. S. square inch and an elongation in 2 inches of about 2 per cent, Air Service Specification 11,010-B in three classes-Special, very useful for intricate castings, where abrupt changes in Grade A, and Grade B-in which the minimum allowable ’ section and thin walls would spell cracks and misruns in the contents of aluminium are 99.5, 99.0, and 98.0 per cent, alloys ordinarily employed in the foundry; and the prorespectively. Chemical analysis of a number of shipments prietary and lees well known 1 magnesium-1 silicon alloy, of metal in each of these which requires heat treat1 ment and develops tensile grades has shown a silicon i properties similar- to those range of from 0.04 to 0.20 The 5 per cent silicon alloy of aluminium, at least, per cent in the ingot of of the 4.75 copper-0.75 silihas attained importance as an engineering material. special quality from 0.14to con alloy. Small additions of silicon increase the strength and In general, the addition 0.54 per cent in Grade A; hardness of aluminium rather slowly, but decrease the of silicon to aluminium-base and from 0.30 to 0.94 per percentage of elongation less rapidly than does any coma l l o y s i n a m o u n t s over cent in Grade B. monly added metal except zinc. Suitable heat treatabout 1.0 per cent is felt in Silicon plays a more imment markedly improves the ductility of the alloys, portant role, however, as t w o d i r e c t i o n s . In the without impairing their strength or hardness. The foundry, silicon contributes an added constituent in the metallography of the series is described at length, and binary and polynary sandstrongly to ease of manipucomment is made concerning the interpretation of preslation, diminishing shrinkcast alloys of aluminium ent related equilibria diagrams. 1 age, porosity, and susceutibase. A true classification of the silicon-bearing alloys I I b&t; to hot shortness. i n d of aluminium necessitates increasing the fluidity of the making a distinction between the “normal” and the “modi- melt. These characteristics serve to cut down the number of fied” alloys. As differing from the “normal” alloys, which wasters and to widen the field of castings which can be successare prepared according to ordinary foundry practice, the fully poured. On the other hand, the alloys themselves ac“modified” alloys are those which are manufactured by quire physically both advantageous and disadvantageous propadding to the molten aluminium-silicon mixture a t the proper erties. Silicon hardens the alloys and improves their strength temperature a small amount either of a powder consist- a t the expense of ductility. The presence of iron and maging essentially of an alkaline fluoride or of metallic alkali nesium, which form compounds with silicon, causes greater (with zinc). The modification treatment comminutes the intensification of hardness and loss of ductility than conies particles of silicon, with beneficial alteration of tensile prop- from the action of silicon in the absence of these elements. erties. The improvement in strength and ductility im- The resistance to atmospheric corrosion and the lightness posed upon the alloys by modification is lost wholly, or partly, of the alloys are also enhanced. On the other hand, the on remelting. alloys containing more than about 1.5 per cent of silicon Among the commercially useful binary alloys are the nor- do not machine readily. This property is not particumal 5 per cent and the modified 13 per cent silicon alloy. larly detrimental, however, a8 it engenders merely the adBesides these simple alloys there are the proprietary 4.75 justment of the machining practice to the peculiarities of copper-0.75 silicon alloy, from which an ultimate strength the alloy. of about 30,000 pounds per square inch and an elongation in In the binary series itself silicon hardens the metal and 2 inches of about 6 per cent may be readily attained after improves the ultimate strength quite rapidly for additions suitable heat treatment, thus making it adaptable for mod- up to 5 per cent; then slowly to a maximum of about 22,000 pounds per square inch near the eutectic (about 11 per cent I Received November 28 1924. Published by permission of the Chief of silicon) point; beyond this point, up to 18 per cent of of Air Service, War Department
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silicon a t least, the ultimate strmgth gradually At the same t m e , the percentage of elongation falls continuously, but at a much less rapid rate than is occasioned by adol'n..~ ditlnrls of copper in the qiin;lo These a ~ u n i l r ~ ~ i ~ n ~ - sai ~hl cvs, o n whilP ,,~. fOlIlld1~aiiributes especial'i-y in the h$z:eQtectic range of billcon, moderately good t e n 4 e pronert;,-, relative soundness, and a high degree of resistance to corrosion, have a relatively low proportional h i t and modulus of rupture nfimmn-
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Silicon per Cent. Figure 1-Partial
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lMethods of Alloying
SI
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the eutectic. Iron, an impurity, occurs possibly in two forms-as the iron (aluminium) silicide, and as the iron aluminide (FeA13). What copper there is in the aluminium ingot +he l ~ o r * d n ir ~ retained as copper aluminide (Cui%) in ;n the aluminium, Still another unidentihd un I,. . - . impurity is obscri ble in the series. The present
