X .— M ETALS; METALLURGY, INCLUDING ELECTRO-METALLURGY
A. The following explanation of this behaviour, which is independent of the shape of the ingot within wide
limits, is given. When the molten metal is poured into the mould the first crystals appear as dendrites extending inwards perpendicular to the walls of the mould, the length of the dendrites increasing towards the top of the ingot where the rate of cooling increases.
At a certain stage in the cooling contraction is so great th a t the solid shell shrinks away from the mould and further cooling proceeds more slowly; the ferrite crystals formed in this period appear generally through
out the still liquid mass and fall to the bottom of the central liquid cone, while the globules of sulphide which are thrown out of solution rise through the liquid and become attached to the dendritic crystals first formed, thus forming a conical zone of sulphur-rich metal round an inner core of almost pure ferrite. The sulphide globules form nuclei for the crystallisation of phosphide and carbide, which therefore tend to segregate below and throughout the sulphide zone. The smaller V- shaped segregations a t the top of the ingot are due to suction effects on the final very impure liquid metal which is forced towards the top a t the end of the solidifi
cation. A. R. Po w e l l.
H ardness and structural changes on heating cold-rolled steel containing 1 15, 0 -90, or 0 -60% C.
R. Jo n s o n (Jernkontorets Annaler, 1929, 207—235;
Chem. Zentr., 1929, ii, 1064).—The temperatures at which recrystallisation begins and ends are the higher the higher is the carbon content. The optimum tempera
ture lies between 650° and the Acl point. Structural changes accompanying recrystallisation were not
observed. A. A. El d r i d g e.
S ystem sulphur-iron-carbon. H . Ha n e m a n n and A. S c h i l d k o t t e r (Arch. Eisenhiittenw., 1929—1930, 3, 427—435 ; Stahl u. Eisen, 1930, 50, 42—43).—The quasi-ternary system iron-iron sulphide-iron carbide contains a ternary eutectic (m.p. 975°) with 87% FeS, 2-5% Fe3C, and 10-5% Fe ; there appears to be no ternary solid solution a t the Fe3C corner of the ternary diagram and only a small range in the iron corner as the solid solubility of sulphur in iron does not exceed about 0-03%. The solubility of iron in ferrous sulphide at the ternary eutectic temperature is about 3%, and that of Fe3C in iron at the same temperature is 20%. Molten mixtures having a composition indicated by any point on the straight line joining the Fe-Fe3C eutectic point to the Fe-FeS eutectic point in the triangular diagram separate into two liquid phases, the upper containing 0 • 22% C and 30-65% S and the lower 4-12% C and 0-98% S . The determination of small quantities of carbon in alloys with a high sulphur content is unsatis
factory by the usual combustion method, as not all the sulphur dioxide is retained by the chromic acid tubes.
I t is preferable, therefore, to collect both sulphur dioxide and carbon dioxide in a concentrated solution of sodium hydroxide free from carbonate, then to oxidise the sul
phite with permanganate, and finally to acidify the solution with sulphuric acid and expel the liberated carbon dioxide into a measured excess of 0 • liV-potassium hydroxide : after addition of barium chloride the excess of alkali is titrated with 0-liV-oxalic acid, using phenol- phthalein as indicator. A. R. P o w e l l .
B r itis h C h e m ic a l A b s t r a c t s— B .
C l. X .— Me t a l s ; Me t a l l u r g y, i n c l u d i n g El e c t r o- Me t a l l u r g y. 243
[Resistance to corrosion of] cast iron containing nickel and copper. M. Ba l l a y (Rev. Met., 1929, 26, 538—553).—The microstructure and resistance to corrosion of 15 cast irons containing up to 15-6% Ni, 6-5% Cu, and 2% Cr have been investigated. The most resistant alloy of those tested was th a t containing 2-16% Si, 15-63% Ni, 5-76% Cu, and 1-28% Cr ; this withstood cold dilute mineral acids, acetic acid, and sea
water as well as or better than a good bronze, but was more readily corroded by hot sulphuric acid. The alloy has an austenitic structure, is easily worked, and does not scale badly at high temperatures.
A. R. Po w e l l.
S ystem iron-phosphorus-carbon. R. Vo g e l
(Arch. Eisenhuttenw., 1929—1930, 3, 369—381; Stahl u. Eisen, 1930, 50, 14—15).—In the binary system iron-phosphorus, alloys with up to 21% P contain the constituent Fe3P when cooled rapidly and Fe2P when cooled slowly, the former being in stable and the latter in unstable equilibrium. The a—y transformation region in phosphorus-iron alloys is a closed field, as is the y-region ; the maximum solid solubility of phos
phorus in a-iron is 0 • 6% and in y-iron 0• 25%. Addition of phosphorus to iron-carbon alloys reduces the solid solubility of carbon at all temperatures. In the system Fe-Fe3C-Fe3P there are (i) five primary liquidus surfaces, at the temperatures of which there separate from the liquid phase on cooling ternary a- or 5-solid solution, ternary y-solid solution, cementite, Fe2P, and Fe3P ; (ii) corresponding secondary surfaces of equilibrium between two of the above crystal phases and liquid;
and (iii) two planes of equilibrium between three crystal phases and liquid, namely (a) a transition plane a t 1005°, the phases of which are : a-solid solution with 0-3% C and 2-2% P, y-solid solution with 0-5% C and 2% P, liquid with 0-8% C and 9-2% P , and the phosphide Fe3P ; and (b) the plane of the ternary eutectic a t 950°, with the phases y-iron with 1 • 2% C and 1 • 1 % P, Fe3P, Fe3C, and liquid with 2-4% C and 6-89% P.
Owing to the transformations which iron undergoes in the solid state and to the irregular contour of the fields of existence of the various phases, the study of the equilibria in solid ternary alloys is highly complicated ; thus, on cooling some of the alloys, a new phase may separate a t a certain temperature and redissolve again at a lower temperature. In alloys in which a t 745°
two three-phase equilibria occur, viz., (a) between a-iron containing 0 • 1 % C and 1 • 5% P, y-iron with 0 • 8% C and 1% P, and the phosphide Fe3P, and (b) between y-iron, Fe3P, and Fe3C, a reaction takes place between the four phases which results in the slow disappearance of the a-iron and Fe3P. Thus in alloys with a low phosphorus content the constituent Fe3P disappears a t 745° ; during cooling to 720° a further reaction takes place, the y-iron solid solution decomposing into pearlite in which the ferrite constituent contains a t the most 0-1% C and 1-5% P. The temperature of the pearlite transforma
tion point in steels is therefore raised slightly by the presence of phosphorus, the maximum temperature
being 745°. A. R. Po w e l l.
D e t e r m i n a t i o n o f t u n g s t e n , c h r o m iu m , a n d v a n a d iu m in h i g h - s p e e d t o o l s t e e l s . W . Br u g g e
-mann (Chem.-Ztg., 1929, 53, 927—928, 947—950).—
For the determination of tungsten a sample of the steel (1—5 g. according to the tungsten content) is dissolved in 50—100 c.c. of 1 : 2 hydrochloric acid together with a drop or two of hydrofluoric acid if much silicon is present. The solution is slowly evaporated to about 20 c.c. and the iron and tungsten are oxidised by the cautious addition of just sufficient dilute nitric acid ; after boiling for 3 min., 100 c.c. of boiling water are added and the tungstic acid is collected on a pulp filter, washed first witli dilute hydrochloric acid and then with 1% ammonium nitrate, ignited, and weighed. No silica is contained in the precipitate, but in tlie case of poorly heat-treated steel some chromium carbide may be undecomposed by the above treatment. In this case the ignited precipitate is fused with sodium hydroxide a t a low temperature and the tungsten precipitated as mercurous tungstate from the filtered solution of the fusion. An aliquot part of the acid filtrate from the tungsten is evaporated with 10 c.c. of sulphuric acid and 10 c.c. of phosphoric acid until fumes just begin to appear, 500 c.c. of tap water are added, and the chromium is oxidised to chromic acid by boiling with 5 c.c. of 0-5% silver nitrate solution and 10 g. of ammonium persulphate until bubbles of oxygen cease to appear. The silver is precipitated and any permanganic acid destroyed by further boiling with 5 c.c. of 1 :1 hydrochloric acid until the silver chloride coagulates and settles readily. After cooling, a slight excess of ferrous sulphate solution over th at required to reduce the chromic and vanadic acids is added and the solution is titrated with permanganate. The difference between the amount of permanganate required for the volume of ferrous sulphate solution alone and th at required after addition of the assay is calculated to chromium, a small allowance of 0-1—0-3 c.c. being made for errors in obtaining the end-point. An excess of ferrous sul
phate is added to the solution after titration of the chromium to reduce vanadic acid to vanadyl sulphate, the excess of ferrous sulphate is oxidised by addition of ammonium persulphate to the cold solution, and the vanadyl sulphate is titrated with permanganate. The persulphate excess is without action either on vanadyl sulphate or on permanganate in cold solutions.
A. R. Po w e l l.
P erm eability of m etals to gases. Classification of the various gas-m etal sy stem s. V. Lombard (Rev.
Met., 1929, 26, 519—531).—Recent work on the diffu
sion of gases through metals is critically reviewed and an attem pt is made to deduce an equation which will express the rate of diffusion of any gas through any metal. The closest approximation to the experimental results is afforded by the expression d — K { \ / p / h ) XlO"4, where K and d are constants which are different for every system, p is the pressure of the gas on one side of the metal (the other being in a vacuum), h the thick
ness of the metal, and t the absolute temperature. The various systems so far investigated are arranged in order of decreasing permeability of the metal a t 500° as follows: hydrogen-palladium, hydrogen-mild steel, hydrogen-electrolytic iron, hydrogen-nickel (1% Co, 0-5% Fe, and 0-15% Si), hydrogen-electrolytic copper,
aa
B r itis h C h e m ic a l A b s t r a c t s — B .
2 4 4 Cl. X .—M e t a l s ; M e t a l l u r g y , i n o l u d i n o E l e o t r o - M s t a l l u r o y .
hydrogen-electrolytic nickel, hydrogen-zinc, carbon monoxide-mild steel, helium-nickel, liydrogen-plat- inum, argon-nickel, nitrogen-nickel, oxygen-silver, hydrogen-aluminium. A. R. Po w e l l.
Corrosion of m etals and alloys. A. Po r t e v in
(Rev. Met.., 1 9 2 9 , 26, 60 6 — 631, 6 3 5 — 6 5 4 ).—A review of recent work on corrosion, detailing the nature and cause of the various types of corrosion of steel, copper alloys, and light alloys, and the numerous methods of studying the rate of corrosion and the value of protective coatings. Research directed towards the production of incorrodible alloys such as stainless steels is discussed with especial reference to the theoretical aspect of the
subject. A. R. Po w e l l.
Action of water on alum inium vessels, and the effect of alum inium com pounds on the organism .
C. Ma s s a t s c h (Hausz. V.A.W. Erftw. Alum., 1929, 1 , 75— 88 ; Chem. Zentr., 1 9 2 9 , ii, 1 2 1 2 ).—Experiments with pure aluminium and silumin and different waters a t the ordinary temperature and a t 8 0 ° show th a t the extent of attack is of the same order as with other metals.
Acid foods cause greater corrosion than fatty foods.
Alumina is physiologically harmless.
A. A. El d r i d g e.
Copper-aluminium [alloys] containing m angan
ese, tin, or cobalt. E. Mo r l e t (Rev. Mdt., 192 9 , 26,
46 4 — 4 8 7 , 5 5 4—5 6 9 , 5 9 3—6 0 5 ).—Full experimental details are given of work on the effect of manganese, tin, and cobalt on aluminium bronzes containing 8 0—9 0 %
Cu, the chief results of which have already been pub
lished (A., 1 9 2 9 , 9 9 5 ). Quenching of alloys with tin or manganese from 8 5 0 — 9 0 0 ° generally produces a martensitic structure. The solubility of cobalt in alloys with a structure consisting of a + ( a - f y) increases with rise of temperature. Excess of cobalt over the limit of solid solubility results in the appearance of needles of a new constituent along the grain boundaries ; this constituent is insoluble in « but dissolves in y to a limited extent. A. R. Po w e l l.
Reduction of zinc oxide by m eans of gaseous carbon monoxide at atm ospheric pressure and at high pressures. 0. Do x y (Bull. Acad. Roy. Belg.,
1929, [v], 15, 254— 2 6 4 ).—The reduction of zinc oxide by gaseous carbon monoxide a t 1100° proceeds more rapidly than in the usual commercial method by means of solid carbon. Increase of pressure favours the rate of production of the metal. 0 . J. Wa l k e r.
Zinciferous slags and the rotary [furnace] pro
cess. W. St a h l (Chem.-Ztg., 1930, 54, 79).—The zinc in the slags of the zinc- and lead-smelting industries is mainly present as ferrite, ZnEe20 4, although a little is in the form of silicate and of zinc oxide mechanically retained in the slag. The method of recovering the zinc by roasting the slag with coke in rotary furnaces is described; during this process deposits containing a considerable proportion of metallic iron are formed in
them. H. F. Ha r w o o d.
T reatm ent of residues from [the working-up of lead ores b y ] the Harris process. F . Vo g e l(Chem.- Ztg., 1 9 3 0 , 54, 4 9 — 5 0 ).—A discussion of the economics of treatm ent of the residues for recovery of antimony
and tin. S . I . Le v y.
Rapid determ ination of iron in nickelf-plating]
baths. 0. Gr u b e (Chem.-Ztg., 1929, 53, 935).—Into a 10-c.c. centrifuge tube are placed 5 c.c. of the solution to be analysed, 4 c.c. of 35% sodium acetate solution, a few drops of acetic acid, and 1 c.c. of 1% potassium chlorate solution, the mixture is heated for 10 min. in a boiling water-bath, and the tube placed in the centri
fuge and rotated for 3 min. a t maximum speed. The volume occupied by the precipitate multiplied by 20 gives the weight ing. of ferrous sulphate (FeS04,7H20) per litre of electrolyte sufficiently accurately for tech
nical purposes. A. R . Po w e l l.
Enam elling of cast iron. Kr y x it s k y and Ha r r i-
sox.—See VIII. Alum inium v essels for culinary purposes. Th i e m e.—See XIX.
Pa t e x t s.
Blast-furnace operation. W . A. Ha v e x (U.S.P.
1,738,577, 10.12.29. Appl., 9.4.27).—The pressure of the blast supplied to a furnace is caused to fluctuate by means of a rotary pump and pulsator. C. A. Ki x g.
Blast-furnace tuyère. E. H . Ho l z w o r t h (U.S.P.
1,738,901, 10.12.29. Appl., 11.7.27).—The nose of a tuyère is jacketed with an air chamber from which a jet of air is directed downwardly into the molten metal adjacent to the mouth of the tuyère. C. A. Ki x g.
H ot-blast cupola. C. D. Ba r r, Assr. to Am e r. Ca s t Ir o x Pi p e Co. (U.S.P. 1,738,277, 3.12.29. Appl., 15.11.27).—To form a recuperator for a cupola, rect
angular blocks of iron or other material are set round the refractory lining and are connected together by means of tapered nipples. As many rings are installed as may be necessary. Air from a compressor enters an upper chamber and travels helically down the recupera
tor blocks to a bottom collecting chamber, out of which the tuyères are supplied. C. A. Ki n g.
M elting and refining furnace. T. F. Ba il y
(U.S.P. 1,739,343, 10.12.29. Appl., 28.1.28).—A melt
ing furnace heated by electric arc is superposed on a refining furnace of crucible type provided with a bottom electrode and a ring electrode near the top. Molten metal runs from the upper furnace into the refining furnace through a layer of slag above the refined metal, which is tapped from the lower p art of the furnace.
C . A . Ki n g.
M elting furnace for m etals. R e b o u r g & D o t o n t ( F .P . 634,113, 10.5.27).—The furnace comprises an upper melting chamber, in which the charge is placed on a mushroom-shaped support and melted by the flames of an oil burner which play around the support, and a lower collecting chamber in which the molten metal is further heated by induction to the desired casting temperature. Oxidation of the molten metal is thus almost completely prevented. A. R . P o w e l l .
Continuous-heat annealing furnace. F . J . Wi n d e r, A s s r. t o Al l e g h e x y St e e l Co. (U .S .P . 1,738,130, 3.12.29. A p p l., 30.3.28).—T h e l e n g t h o f a s h e e t- a n n e a li n g f u r n a c e is s u f f ic ie n t t o a llo w o f t h e p r e h e a ti n g , a n n e a lin g , a n d c o o lin g o f t h e s h e e ts w h ic h a r e s u s p e n d e d e d g e w is e f r o m t h e t o p a n d c a r r i e d b y t r a v e l l i n g m e a n s o n t h e s id e w a ll o f t h e f u r n a c e . T h e f u r n a c e m a y b e
B r itis h C h e m ic a l A b s t r a c t s — B ,
C l . X I.—E l e c t r o t e o i i n i o j . 245
closed to allow the internal atmosphere to bo con
trolled. C. A. Ki n g.
Coating of m etal articles w ith m etal. J . v o n Bo ssk ( B .P . 323,847, 1.11.28).—The metal article is given a preliminary coating with, e.g., nickel, then treated as is described in B .P . 286,632 ( B ., 1928, 677) to remove occluded gases, again coated with a second metal (e.g., chromium), and finally degassed. The process is of use in the production of sliding surfaces for light- metal cylinders for internal-combustion motors.
EL Ro y a l- Da w s o n.
Tubes or flexible hose-pipes w ith an internal non-rusting coating. 0 . Me y e r- Ke l l e r & Ci e.
(Swiss P . 123,773, 22.7.26).—Metals bands from which the tube or hose is to be made by means of a longi
tudinal weld or by spiral winding and welding are previously coated on one side by the spraying process with a metal which is resistant to corrosion and which has a higher m.p. than the metal of which the bands are made, so th a t it remains unaffected during the subsequent
welding. A. R. Po w e l l.
Recovery of silver and lead from their pure oxides. Soc. Me t a l l u r g. Ch i l e n a “ Cu p r u m ” ( 6 . P .
450,229, 5.6.23. Addn. to G .P . 447,686 ; B., 1930, i0< )-
—Calcium chloride is used instead of sodium chloride in the leaching solution. A. R. Po w e l l.
Oxalate bath for electrolytic tinning. St u d i e n- Ge s. f. Wir t s c h a f t u. In d u s t r i e m.b.H . (G.P. 457,874, 13.5.26).—The bath comprises a saturated solution of ammonium oxalate, oxalic acid, and ammonium chloro- stannate, to which is added dithionic acid.
A . R . Po w e l l.
Cadmium plating. C. H. Hu m p h r i e s(B.P. 309,071, 5.3.29. U.S., 4.4.28).—A sugar, such as barley sugar, cane-sugar caramel, malt sugar or syrup, is added to the acid cadmium bath to secure a bright, homogeneous, and coherent deposit. H . Ro y a l- Da w s o n.
Hardening m etal articles by nitrogenisation.
A. Fr y, Assr. to Nit r a l l o y Co r p. (U.S.P. 1,737,711, 3.12.29. Appl., 31.10.28. Ger., 17.11.27).—See B.P.
300,633 ; B., 1930, 63.
A lum inium alloy. H. C. Ha l l and T. F. Br a d b u r y, Assrs. to Ro l l s Ro y c e, Lt d. (U.S.P. 1,744,545, 21.1.30. Appl., 27.3.29. U.K., 3.4.28).—See B.P.
300,078 ; B., 1929, 24.
Tunnel kilns (U.S.P. 1,737,540). Separation of ores (B.P. 303,810).—See I. Electric furnace (U.S.P.
1,739,344).—See XI.
XL— ELECTROTECHNICS.
Electric heating [for rectifying stills] and fur
naces. 0 . Do n y (Bull. Acad. Roy. Belg., 1 9 2 9 , [v], 15,
2 4 3—2 5 3 ).—Soft iron, in the form of rods at least 5 mm.
in diam., is recommended as the heating resistance for electric furnaces. Temperatures up to 1 2 0 0 ° can be maintained for long periods, and the internal volume of the graphite furnace described can be as high as 15 litres without using more than 2 0 0 amp. A lead rectifying still, in which the heating source consists of a soft-iron filament immersed directly in the liquid, is described.
By adjusting the filament current the speed of the
distillation can be regulated very exactly, and it is possible, for example, to purify toluene completely from tliiophen by distillation alone. 0. J. Wa l k e r.
M anganese dioxide for dry cells. I, II. S. Ka n e k o,
C. Ne m o t o, and S. Ma k in o (J. Soc. Chem. Ind., Japan, 1929, 3 2 , 205 b, 206 b).—I. The E .M .F . and capacity of a dry cell are independent of the manganese dioxide content of the oxide used, bu t are larger in the case of artificial oxide than in the case of the natural substance ; the coarser-grained oxide gives the higher E .M .F . The relations between the capacity and the grain size and the rate of discharge arc irregular.
II. X-Ray examination showed th a t various kinds of natural manganese dioxide, such as pyrolusite and psilomelane, have the same crystal structure, and th at natural and artificial dioxide have different crystal
structures. S. K . Tw e e d y.
R ussian asphalt. Gr a e f e.—See II. Electro
m agnetic separators. Box.—See V III. Nickel- plating baths. Gr u b e.—See X. Acidity of oils.
Se l t z and Si l v e r m a n.—See X II. Electrodialysis cell.
Cr o w t h e r and Ba s u.—See XVI. Electrodialysis of m olasses. Ka m e y a m a and Ma y e d a.—See XVII.
Pa t e n t s.
Electric furnace. T. F. Ba i l y (U.S.P. 1,739,344, 10.12.29. Appl., 28.1.28).—In a furnace of inverted-cone shape, adapted more especially for the production of synthetic pig iron from scrap steel, an electrode is arranged a t the lower smaller end and movable electrodes a t the upper end are adapted to be moved downwards in paths substantially parallel to the side walls of the furnace and in alinement with the upper end of the lower electrode. The upper part of the furnace side walls may be lined with carbon for conveying part of the current. The furnace is provided with a central charging opening a t the top and a removable bottom carrying the bottom electrode. J. S. G. Th o m a s.
E lectric furnace [for producing carbon disul
phide]. P. Br o w n, Assr. to Br o w nCo. (U.S.P. 1,737,566, 3.12.29. Appl., 17.6.25).—Sulphur and charcoal are introduced into the furnace a t a temperature near or within the optimum temperature range (800—1000°) of the reaction C + 2S = CS2. The furnace comprises a jacketing or heating chamber surrounding a reaction chamber throughout which the desired temperature may be maintained. The jacketing chamber wall is con
structed of heat-conducting refractory material, and a pair of electrodes is arranged near the bottom of the reaction chamber. J- S . G . Th o m a s.
Inductor furnace. E. F. No r t h r u p ( B .P . 316,659, 14.5.29. U.S., 2.8.28).—The outer part of the furnace is protected against stray magnetic fields by surrounding the inductor coil by an auxiliary coil, the current in which produces a magnetic field assisting the return magnetic flux in the space between the two coils, but opposes and approximately balances the return flux in the space outside the auxiliary coil. J. S. G. Th o m a s.
[High-power] electric induction furnace. Al l m a n n a Sv e n s k aEl e k t r is k a Ak t ie b o l a g e t(B.P. 310,031, 12.4.29. Swed-, 21.4.28).—Parts of the winding of the
B r itis h C h e m ic a l A b s t r a c t s — B .
240 Cl. X I .— El e c t k o t k o h n ic s.
generator or transformer feeding the furnace are con
nected between the several series-connected portions into which the primary winding of the furnace is divided.
The power factor is corrected by condensers connected in series or in parallel with each of the furnace-winding
portions. J. S. G. Th o m a s.
[Mounting of resistors in] electric furnaces. A. N.
Ot i s and G. W. He g e i., Assrs. to Ge n. El e c t r ic Co.
(U.S.P. 1,738,446, 3.12.29. Appl., 24.10.28).—An electric heating resistor is removably mounted on a refractory framework and secures the latter to supports in the furnace side walls. J. S. G. Th o m a s.
Electrical resistance and its formation. H.
Pe n d e r and J. H. Mu e l l e r (U.S.P. 1,739,256, 10.12.29.
Appl., 22.8.24).—A film of germanium is formed on the
Appl., 22.8.24).—A film of germanium is formed on the