US2259457A

US2259457A - Powdered metal and alloys

Info

Publication number: US2259457A
Application number: US184703A
Authority: US
Inventors: Croll William Andrew
Original assignee: Individual
Current assignee: Individual
Priority date: 1938-01-12
Filing date: 1938-01-12
Publication date: 1941-10-21
Anticipated expiration: 1958-10-21

Description

Patented oe'z1,.1941 r scram rownaasn mar. sun armors William Andrew Croll. Norrlstown, Pa.

No Drawing.

Serial No. macs scum. (a. zsz-sosl My invention relates to ilnely divided metals, alloys, metallic, compounds and various other materials which it is desired to produce in powdered form,,and the method of forming the same. More specifically my invention relates to con-' verting to powdered form stainless steel, .tungsten, molybdenum, tantalum, titanium and their carbides: the double carbides of tungsten and titanium; the metals nickel, cobalt, copper, lead, zinc, graphite, iron oxide, Bakelite (phenolformaldehyde condensation product), tin, Prussian blue, silver and other precious metals, and various metallic and n -metallic materials which are crushable and which it is desired to obtain in powdered form.

I can convert these materials to such flnelv divided form that they can form substantially permanent suspensions in liquids" such as water vided form. 1

Application January 12, 1938,

prevents oxidation and makes available such materials in this desirable finely powdered form. An outstanding example of such material that hitherto has been found impossible to powder because of its oxidizing tendencies is Swedish iron. Powdered Swedish iron can be produced according to my process and shows no tendencies to oxidize after being reduced to this .flnely di- Further, because I can obtain with myprocess, I can form susf are substantially permanent in that for practical and are susceptible to. Brownian movement.

Metal powders have long been made since'they have a.great commercial value in certain processes. Thus, metallic objects can be formed from metal powders instead of from' east molten metals and definite advantages such as purity of prodtain alloys in powdered form. This is because customarliy'powders were made by depositing the metal as by chemical precipitation or by elec-, tric deposition followed by grinding the so formed metal to the desired powder size. Since alloys cannot be chemically precipitated or electrolytically deposited, they cannot be formed in powders.

materials of a finer particle size than any hitherto produced. In addition, I can powder alloys and certain other materials which it has been found impossible to powder heretofore according to the known processes. Because of the particle size which I produce, I secure superior results in the formation of molded metal objects. The flaws that have hitherto been incidental to the casting processes are completely eliminated by the use of my powders.

I can also combine certain metals such as copper and tungsten which cannot be produced in the ordinary alloy forms. Because I obtain these metals in-such fine particle size, I can'combine them in desired proportions to obtain rinlshed products-oi predetermined qualities. Thus. a new held of combinations 0! metals for desired purposes, which metals cannot be alloyed by the ordinary means, is opened .by my process.

Further, my process aflords to certain easily oxidizable materials, a surface protection that According to my process, I can form powdered water mixture that is placed in the ball mill,

commercial purposes they will not settle out. w process involves crushing material to be ground as for example in a ball mill in such a way and under. such conditions so that when separation-of one particle fromthe mass is effected by the crushing means, certain substances present in the mixture which will not chemically react with the crushedmaterial, surround the particle and carry it away from the mass so that it is exposed for further crushing without impairing the crushing efl'ect'on the larger mass from which it hasbeen separated; Thus, .it is the purpose of my invention to continuously form a suspension of the small particles of the material to be ground in the ball mill so as to proof the balls of the ball ,mill.

Specifically, for example, in the crushing of the metal, I add to, the customary metal and saponin and an aukiliary material such as salacin. 'I'he saponin acts to separate the crushed particles one from the other'and to create more or less of an'emulsion of the materials in the water. The salacin prevents the saponin from forming a froth and has a certain separating action in itself. In lieuof the saponin, I may use any sap type or material. In lieu of the salacin, I may use any material that can be converted to a dextrose, such as salacin, papain, lactose or sugar,

and also materials of the tannic acid and gallotannic acid groups:- It is extremely important that-quantities of the materialsselected be such that no froth or foam. be formed in the ball mill.

I have found that a great numberof thematerl'als which are ground to line particle size according to my invention when thrown into water move about in the water in conformity with what is known as the Brownian movement. That is, the particles continuously move toward and away from each other in unceasing movement. This apparently is' due' to the fact that the particles I are in such fine finely divided form.

oi the line particle size which steel, tungstemmolybdenum, tantalum, titanium and their carbides;the double carbides of tungsten and titanium and the metals nickel. cobalt, copper, lead, zinc, graphite, silver and other precious metals, iron oxide, Bakelite, tin, Prussian blue and various metallicand non-metallic ma- A further object of my invention is to convert crushable materials to finely powdered form.

A further object of myinvention is to produce such alloys, metals, metallic and non-meanness? the level of the pebbles or balls'is mini w the 'drawn. The liquid that has been withdrawn 1 out of the mixture. 11 desired, the liquidcanbe boiled-H This results in the deposition tallic materials and plsments'in such a state or subdivision that they are susceptible oiBrownian movement.

A further object of my invention is to provide a novel process for the production of extremely finemietal powders.

A further object of my invention is to produce these extremelyfine powers by means of a ball milling operation substantially without using a foam.

. It is a'further object of my invention to pro-, -vide a mixture'of crushable material. water-and eepehih roithe ball mill grinding.

It is a further object of my invention to provide a mixture of crushable material. water,

saponin and a material capable of being-converted to adextrom for theball'rnillgrlnding.

of the minutely divided stainless steel. Alternatively the stainless steel can be extracted by adding an acid which reacts with-the ammoniacal solution to precipitate the finely divided stainless steel. This acid can be a-mineral'acid such as sulphuric acid or hydrochloric acid. Again, a salt such as sodium chloride or caustic alkalis may be employed. Further,-'the solid particles maybe extracted from the liquidby means of a According to my preferred method. I employ a ball mill comprising a cylinder; with a number of grinding pebbles. balls or rods contained therein. The cylinder is adapted to be rotated about a horizontal axis so as to cause the pebbles, balls or rods contained therein to be tumbled. upon themselves whereby they thoroughly-crush and grind any material distributed therethrough. In this'ball mill machine, I place a mix comprising.

- Nat centrifuge. Each quantity of liquid drawn'oi! from the ball mill as above-indicated yields at least one-quarter ounce of -the finely divided stainless steel.

The operation which I have described is a continuous grinding operation, ground metal being drawn of! at periodic intervals and metal to be ground being added as each charge is withdrawn ,aftertheinitialgrindingoperation. the grinding periods are shortened.

' Another good mixture for the production of finely divided stainless steelis.

Stainless steel os 4 Quillaia extract -os. (liduidL- 1 Gallotannic acid ....mg Ammonium hydroxide e -.-..os 1 Water 2,000

Stainless steel "'06-.. 4 Quillaia extract ce Ammonium hydroxide cc 15 Water M 2,000 1 saponin and calcium oxalate. One ounce of the quillaja wood is digested with one pint of warm water. 'lhewoodisiefttodigestinthewarm water for a period of about one hour and then filtered. The filtrate is known as. quillaja extrec whehthie extract is boiled. as shall he ckscribed later in this specification, it is converted into sapogenin (2141133010 and glucose.

. This sapogenin is insolublein water. In placeol the quillaia extract, saponin (senegin) CuHeeQio' maybeemv oy dr Themillwiththemixcontainedthereinis I have found that a great variety of metals. metallic compounds and pigments may be ground to this desired finely divided form, and below I have set forth a large number of examples of the preferred mixtures for such metals, etc.

In the following examples, the quantity of ma terlal to be ground is gauged by the operator according to the increase in bulk which takes place during the grinding operation. Thus. while graphite increases in'bulk four times Bakelite-(phenolrormaldehyde condensationprodportions of the ingredients set forth are approxiturnedfor about 48 hours to thoroughly grind the 1 stainlesssteel. This grinding period may 1,. 1

viously be varied depending on the degree of fineness desired. After this grlndingperlod, the mill is opened and the iiquid'is takenout down to the leva of the, pebbles. The liquid taken out isreplace'd by amixture of about 15 cc'.ofam monium hydroxide and 'sufiicient.metal to replace that withdrawn in the change andenough water to make up the quantitative difierence of is again rotated for a period of about five hours. Th

a large five ton mill to about 50 12.1. II. for

mateandicanbevariedtoacertalnextent Tungsten carbide e 8 Quillija extract -..os.. 1 Gallotannic acid.-..-. -.mg-." 60. Lactose 188-- 00 Ammonium hydroxide .os.. 1 Water ccu 2,000

Iron, as for exampl Swedish iron ..oa y 4 Salicin mg... 50 Tannic a I log" 50 Ammonium hydroxide oz.'. 1' Water.

Copper 7' 4 saponin v I .mL- 20 Balicin mg.- 00.. Ammonium hydroxide. nos... 35' Waiter.

amass-z 3 Q i u 18 Silver 08.. 4 v Calcium carbonate (whitins. chalkor m mg 5 marble) L- 3 Salicin s-- 50 5 Bamn am mg..- Salicinv mg-.. 60 Water. Ammonium hydroxide -,....-ox.- 1

'i water. I Nickel out... 4 19 a g; mg..- 10 o lc oz...- 2 'Iannic ldd 11!.-.50 Balloin 1118-- 50 Ammonium hydroxide "OIL- 1 Sugar (lactose, sucrose, etc.) --ox 5&- Water. Ammonium hydroxide -oz 1 8 Water. a a Cobalt on; V4 is j a Saponin 10 White lea 02.. 'I'annic d l-- Saponin -'---m8-- 0 Ammonium hydroxide ".05..- 1 5 1m mi! 50 Water Ammonium hydroxide -e..-.. ox-.. 1

9 Water. v Y Steel 2-- 4 31 p 5. m -m8-- 10 Red lea 4 Bapon1n m Ammonium hydroxide a 1 'r nni acid ...mg 50 Wa Ammonium hydroxide oz 1 A 10 Water.

Zinc. 1 car. 4 r 22 a v :90 3:;- ga Brick I nin. ..m 10 Ammonium hydroxide 4-0! 1 so gzg m m mi, 50 Ammonium hydroxide- ...-ox-.. 1

11 Water.-

. Lead one- 4 v A 33,

Mica oz 2 Ammonium hydroxide ..-ox..- '1

V Salicin.. mg" 50 m Ammonium hydroxide oz 1 Water. 'I'ln 05-- 4 4|) 24 awn! Alumina -n "05.- 4 Ammonium hydroxide oa.- 1 saponmr "r' Wter 8alicin t-c .mg 50 13 Sugar (lactose or sucrose) on Ammonium hydroxide -ox 1 Iron oxide 0a.- 4 w aaponm mg" 10 8alicin m" 1 In the case of silver, ExampleG, it is preferable m hydroxide 1 not to use ammonium hydroxide since silver ful- Water 50 minate which is highly explosive may be formed.

14 In this case I mayv use an ammonium salt. Further, in connection with certain of the metallic mm blue 4 compounds, as for example Prussian blue-am- 'w monia should not be added in any form since it 50 would react with the iron causing it to turn brown. Obviously, the ingredients of the respec- 15 tive mixer should be carefully selected to prevent m. m "oz" 4 undesirable chemical reactions. 'A low acids 0! m mg 10 the tannin group do not produce best results. Gallic acid mg- 50 so .It isto be noted in each of these examples sam m Wm ponin or its equivalent quilla'ia extract was used. Water. This saponin or saponin type material has the 1' v pectiiiar eflect or lltllfl'omldlllg and separating the sma 1 particles of t e material and carrying these 51m 4 as particles of! into the liquid mix. There the parm 2:" ticles are held in the form of a suspension and are positioned in the best possible manner to receive 0" individually the blows oi the falling balls of the mum -e: 1 ball mill. As I have indicated, it is important wthat the amount of saponin or saponin like m terial in the-mixture be carefully regulated so Bronco powder. -.oa.- 2 tha no froth is formed since the froth has been 3 m 7 mg 10 found to seriously interfere with the woper opernwalit? --mg.'."50-" ation of myprocess. .As is tobe notediromtheae G exampleasalacinorpapainortannicacidor gallotannic' acid or M or gallic acid or conivery useful purpose. 'I'h of a froth and they have with it and, I have found that binations of these are [added and serve a aid in thepreventlon afiiauxiliary action with the saponin in acting to separate the particles-of material. Although their exact action is not fully understood, I have found it to be a fact that their use in combination with the saponin den-' I nitelyimproves' the process. I have also found that I can use this second class of materials without saponin although the results in that case are not as good as when saponin-is employed. .This shows, however, that these materials have a .certaincoating and separating action in themselves. v

- In the powdering of Swedish iron where oxidation is a serious factor these materials which are capable of being converted to dextrose apparently coat the powdered material with a very me almost microscopic coating that aflords protection against oxidation. Ammonium hydroxide is added because of the improved'results obtained mixture causes a vacuum to he created during the grinding process. This vacuum i's believed to be 'of aid in the grinding operation of my invention..

It ismy theory that thefextremely fine metal powders are formed by process as differentiated from the processes -of the prior art for these reasons. Heretofore, in thus ball mills as-the balls or pebbles pounded upon the metal particiesto' its presence in the wan I I I may employ a suitable grinding or crushing 'means.

Asurprisingresultof myproce'sshasbeenthe productionoi pure iron such as Swedish iron in a line powder state without iron oxidising. It has been found'that if iron he powdered according to the priorpzocesses, it oxidizes in WW1 fourhours. Ihavereducediron'tothenne particle size indicated by ray-process and subiected it to an oxidizing atmosphere for three weeks without such objectionable oxidation taking place. These same phenomena have been observed with other easilyoxidizable materials.

A further important feature of my process is production oi powdered hard carbideswithout injury to the grinding mill. Previous attempts to powder hard carbides have resulted in serious cutting of the mill. Further, powdered hard carbides have been produced in one-tenth the time found necessary in preyiouspro'cesses.

Peculiarly' enough. I have found that hard carbides can be easily ground to a fine particle size. according to the prpcess I have set forth.

- This is in marked contrast to the prior grinding processes which have found such carbides extremely diilicult if not impossible to powder;- In

the same way I have found many other materials that are particularly hard in structure easy to produce the metal powder theexternal portion 'oi' the metal particles was-crushed and powdered and the crushed or powdered portion 'of the metallic particle tended to cushion the remaining major portion of the metal particles against 'furthercrushin'g by the'blows of the halls of the ball mill. Thus,"as each particle became partially crushed itbecame increasingly diilicult to elect the subdivision and breaking down of the metal particles of comparatively large size. However. inmymethodassoonastheext'emalportionof the metal particle isfractured or crushed, it is separated andcarrled am by the material which surroundsit if it is sumcientlysmall; The rapid and uniform action ofthe added materials. above" place or pebblemill' water which comprises ticles as reduce to fine particle size. Apparently when in myprocessthesmallpiec'esareheldinam pension apart from the rest of themixture, they are easilyfractured by the blows or the mill.

I claim: l. The process of pulverizing metalswhich comprises fromthe 1 massofmaterial the particles as they are separated from the mass in a water solution containing a saponin and a material that can be-converted into a dextrose leaving the pulverizing metals. which crushing the material; carrying away remaining mass of material the parthey are separated The processiozl'lepulverialng metals 'which crushing. material; carrying-away from the remaining mass of material the w? theyareseparatedfromthe-masina solution containing saponin and an an:-

materiaielpesed for-further crmhing, riodicalbremovingthe-watersoluflon wpowdered suhstancein 5. The process of militarism crushingthcmaterial: particlesasthey remtedn'omthema-in crushing the material; carrying away massoi'materialtheplr-' crushing; and periodically removing powdered subfrom the mass in a the uncrushed mass of- .IIIII of material the e -a,aso, 4s1

rialthat can be converted into a dextrose leaving v the uncrushed mass of material apo'ied ior.iur-- a water solution contaihing saponin and a material that can be converted'into a dextrose'leaving theuncruahed mass oi material-exposed for further crushing; and periodically removing the water solution containingthepowdered substance inlil lmil on. I

8. The process not pulver'izing metal alloys which comprises crushing thematerial; carrying awaytromtheremainingmassotmaterialthe particlesastheyareseparatedtromthemassin a water solution containing saponin andamateriaithatcanbeconvertedintoadextroseleaving theimcrushe'dmassoimaterialelposedi'oriur ther :periodicallyremovingpartoithe crushing water solution containing the powdered sub-' .stance in simpensionrreplacing the removed portion of the water solution with an equal amount of freshwater solution and material to be pulverized together with ammoniinn hydroxide; and

removing the powdered metal from the water solution. 1

"I. The process of pulverizing metal alloys ther-crushing; periodically Pa t of the water solution containing the -powdered substance in suspension; replacing the removed por- I tion 0! the water solution with an equal amount or fresh watersolution and material to be puiverined together with ammonium hydroxide; and removing the powdered metal from the liquid by boiling the water solution.

8.v The process of pulverizing metal alloys which comprises crushing the material; carrying away from the remaining'mass of material the particles as they are separated trom the mass in a water solution containing saponin anda material that can-be converted into a dextrose leaving the uncruahed mass of material exposed for further crushing; periodically, removing'part oi the solution containing the powdered substance in suspension; replacing the remoyed'portion 01' the water solution with an equal amount