US1969396A - Production of metallic articles - Google Patents

Description

Patented Aug. 7, 1934 l,969,396 OFFICE- PRODUCTION OF METALLIC An'ncms Franz Duitschmid, Heidelberg, Germany, assignor.

to I. G. Farbenindustrie Aktiengesellschai't,

Frankfort-on-the-Main, Germany No Drawing. Application January 5, 1931, Serial" No. 506,761. In Germany J 10 Claims.

The present invention relates to improvements in the production of porous or non-porous metallic articles.

I have found that porous or non-porous metal articles are obtained in a particularly advantageous manner when several substances in a finely divided statewhich are capable of being sintered to a coherent mass when in such state, are arranged in a plurality of layers which are difierent from each other according to their composition, and the whole is then subjected to a sintering treatment by mechanical pressure or heat or both mechanical pressure and heat, but without melting, whereby consolidation of the whole mass to a porous or non-porous article occurs. w

The said substances capableof being sintered to a coherent mass may be finely subdivided free metals or metallic compounds which are capable of being converted into the metallic state in which they can be alloyed, or they may be non-metals capable of alloying with the other constituents of the same layer and/or of the adjacent layer or layers. When employing finely divided metals for the said purpose, it is preferable toemploy the metals which have been obtained by the thermal decomposition of the corresponding metal carbonyls, because the metals so obtained are particularly suitable for alloying and sintering. Suitable non-metalswhich may be used according to the present invention are silicon, carbon and arsenic. When employing metal compounds of the aforesaid nature these may be the oxides or other reducible metal compounds, or they may contain the metal in chemical combination with one of the aforesaid non-metals capable of alloying, as is the case for example with the metal carbides. When employing metallic oxides or other reducible metal compounds, it is in most cases necessary to carry out the consolidation by sintering in a reducing atmosphere, but in some cases solid reducing agents present in the mass may be used; thus, when a metallic oxide is present in the mass, the oxygen contained therein may be removed during the consolidation or sintering by interaction with carbon present in the free state or in the form of carbides with the formation of gaseous oxygen compounds of car bon. 50 The conditions under which the consolidation of sintering is carried out depend of course on the nature of the substances to be combined with each other. In many cases consolidation takes 55 readily place by the application of mechanical pressure alone. In other cases, for example when preparing metallic masses in which one of the components is finely divided steel, the mechanical pressure which would be necessary for consolida 00 tion without heat, would be excessively high, and

'with or without the aid of mechanical pressure.

anuar'y 17, 1930 in such cases it is thereforepreferable to eflect the consolidation by heat, without melting, and

When both heat and mechanical pressure are employed, it is possible first to apply heat and only then mechanical pressure, or mechanical pressure may be applied first and the mass then subjected to the action of heat, or heat and mechanical pressure may be applied simultaneously.

The process accordingto the present invention may be carried out for example by charging different metal powders in the form of layers into moulds and then consolidating them to porous or non-porous metal articles by a treatment by mechanical pressure and/or heat without meltmg, which may be carried out either simultaneously or in any sequence and for example while heating directly to the desired temperature or by heating in stages and under a constant of gradually increasing mechanical pressure. The pressure treatment may be carried out by the usual methods such as pressing, rolling, or forgmg, plates, sheets, billets, rods, tubes, wires or other articles thus being obtained. By the process in accordance with the present invention it is possible to prepare metal articles having a composition which varies locally. Thus, metal articles may beprepared in accordance with the present invention, which at different places consist of different metals and/or alloys, as for example articles the surface of which wholly or partly has a composition entirely different from that of the core. Different parts of the surface may also be provided by the process in accordance with the present invention with coatings having diiferent compositions.

A modification of the process'in accordance with the present invention consists in first working up the single layers, of which the final article is to be prepared, into porous solid pieces of which each has a uniform composition throughout, but of which all or several have compositions diiferent from those of the others, the porous solid layers then being consolidated and united with each other by a further treatment by mechanical pressure and/or heat into a porous or nonporous metallic article.

porous consolidated layers; has the, great advantagethat the filling of the mouldswith the finely divided initial substances issubstantially. facilitated; thus, it is as a rulerather; diflicult to are range in a mould'a plurality of vertical layers,

vertical direction I moulds, whereby the aforesaid difliculties in i by welding together two pieces of metal, are ob tained' in a simple manner powders,-

stable to corrosion nobler and therefore more alloy component,

and further consolidated therein mechanical'pressure. Another advantage of'the fact that it 7 cracks or would suffer deformation, individual layers do not adhere firmly together I filling vertical layerscan then" easily be arranged in'a mould in any desired position with or withoutinserting between them layers of pretreatment of several or all of the layers is; the p is possible during such preliminary consolidation-to or mixture of by the preliminary consolidation to a uniform density,;whereby the final consolidation is much Fsimplified: inithatthereisno risk that one or more of the individual; layers shrinkmore than the others, whereby they would be due to adifferent degree of shrinkage. 1

i The importance of the process according to the: present invention consists that bimetals which hitherto have been prepared and that metal'articleshavin'g coatings into sheets without one .of the layerstea'ring or breaking.

It is also possible according to the present invention to prepare metal articles of uniform or substantially uniform composition by subjecting the metal articles to a further heat treatment, following after the first treatment immediately or later, for the purpose of homogenization by diflusion of the constituents of adjacent layers into each other.

The process in accordance with the present invention is also advantageous in that it is possible in the preparation of uniformly composed articles of alloys, for example, to cover a mixture of alloying constituents of the composition of the desired alloy with a layer consisting of the difiicultly oridizable the mass then being subjected to a consolidating treatment by mechanical pressure and/or heat. In this manner .the less noble component in the interior is protected from combustion during the consolidation treatment. If the resulting article then be subjected to a further heat treatment as hereinbefore described, a

' homogeneous alloy having no injury by combus- I moulds with several differentpowders are avoided. These partlyconsolidated 7 pulverulent material, i by heat and/or I employthe conditions which in each are most favourable for the substance substancestreated; thus, different lay'rers of different composition may be brought destroyed by or that the.

the nature of this invention, but the inter an. inthej c directly from metal or heat and of any. desired .composition can be prepared; It is surprising that such non-uniform articles can be rolled out ble for making alloys from iron and one or more cmponents which are more readily oxidized than iron, as forexample silicon, chromium, mange-X- nese or aluminium; the aforesaid disadvantage I of combustion or oxidation of the less noble component was particularly troublesome in the methods hitherto known for producing'such alloys, and disadvantage is overcome according to the; presentinvention, even when carrying invention transformer sheets may be prepared 7 forexampleby consolidating a mixture of iron powder and silicon powderbetweenthin layers of iron powder in the manner hereinbefore described; by sufiiciently extending the heat treat-' ment, the original surface layerfreefrom or poor i-n-silicon may be caused to 'difiusewith the core I of thesheet, so that. completely orpractica'lly completely homogeneous sheets areproduced.

I The process'according to the present invention a is also suitable for the preparation of metal 'articles'havin'g special magneticproperties, for exf ample by working up iayershaving; difierent ferromagnetic properties into an article of nonuniform composition in the manner hereinbefore described. Y

.The following'examples will further illustrate I invention is not restricted thereto. 1 v I I Example 1 I A flat,"rectangularlmould consistingof heat resistingmaterial such as fire-clay, or a chromi- I v um nickel alloy or the steel known in the trade-c.81 NC'I'il steel of thefir'm of Krupp, and-the inner I side of which mould is sprayedwith an aqueous suspension of. magnesium oxide and then dried,

' is'charged with iron powder obtained by the thermal decomposition .of' iron carbonyl, until nine tenth of the form are fil1ed. The remaining mould is then heated in an atmosphere of hydrogen first for 12 hours to 650 C. and then for 6 hours to 1100 C. The compounded sintercd mass obtained is rolled into plates while warm. An iron plate is obtained which is coated with a homogeneous, tight coating of nickel which adheres well. After pickling and glowing, the 1 plates may be further rolled in the cold and finally worked up by the usual heat treatments such as annealing or glowing. The resulting nickel plated metal can be stamped in a very good manner and maybe employed for the manufacture of the most different articles, such as cooking pans or electric fixtures and the like.

Example 2 A mould of the kind referred to in Example 1 nickel and nickel oxide similar to .the first one is filled in as the upper layer. The mould is provided with a cover and is heated for from 3 to 4 hours to 1200 C. in a. reverberatory furnace, whereby carbon monoxide andcarbon dioxide are disengaged and a sintered piece is obtained which 1 space is filledwith 'nickelpowder obtained bythe i thermal decomposition'of nickel'carbonyl, The

consists of three metallic layers connected with each other. The material having a density of about 6 is rolled out in the heat to a sheet nickelplated on both sides. It may be further worked upas described in the foregoing example.

Example 3 Two intimate mixtures of iron powder and nickel powder are prepared, the one containing 36 per cent and the other 41 per cent of nickel. The two mixtures are separately filled into a mould, so that two layers of the same thickness each consisting of one of the said mixtures are formed. The mould is then heated to about 1300 C. in an atmosphere of hydrogen. The resulting sintered material is then rolled out into plates while still having this temperature. The plates are then heated for six hours to about 1200 C. for efiecting difiusion within each of the said layers, whereby, however, no substantial diiTusion between the two difierent layers takes place. The plates are then rolled out into sheets at about 1300" C. In this way bi-metal sheets consisting of two difierent'iron nickel alloys, one with 36 and the other with 41 per cent of nickel, are obtained.

Example 4 Copper powder is pressed at room temperature into a plate having a specific gravity of 3.5. A layer of iron powder obtained from iron carbonyl of five times the thickness of the copper plate is then arranged on said plate and the mass is heated for five hours to about 800 C. in an atmosphere of hydrogen. A coherent sintered mass composed of two layers is obtained which is rolled out into sheet metal at 850 C. In this way a coppered sheet iron is obtained in which the copper coating has about one fifth of the thickness of the whole sheet.

Example 5 Two layers of metallic powders, the one consisting of an intimate mixture of 67 parts of nickel from nickel carbonyl, 28 parts of copper and 5 parts of iron and the other consisting of iron powder without an admixture, are sintered together by heating to about 1000 C. for 10 hours in an atmosphere of hydrogen. The sintered mass is rolled out into sheets at about 1000 C. and the sheets are kept at this temperature for 6 hours. A sheet iron coated on one side with the alloy known in the trade as Monel metal is obtained.

In the appended claims the term mechanical compression moulding treatment is meant to comprise such mechanical treatments as forging or rolling in which the material is subjected to the action of mechanical pressure and simultaneously undergoes substantial deformation.

In the appended claims wherever a metal is referred to, it is to be understood that not only free metals but metal compounds, such as oxides which are capable of being converted into metals under the conditions of working, or metal compounds, such as carbides which are capable of alloying with other metals are contemplated.

What I claim is:-

1. The process of producing metallic articles which comprises arranging a plurality of substances in a finely divided state inadjacent layers of diil'erent composition, .all of said substances being capable of being sintered to a coherent mass when in a finely divided state and at least one of them being a finely divided metal obtained from the corresponding metal carbonyl.

subjecting said layers of material to a sintering. treatment by the action of heat alone and then subjecting the sintered material to a mechanical compression molding .treatment.

2. The process according to the preceding claim in which all the substances used are free metals in a finely divided state.

3. The process according to claim 1 in which all the substances used are metals in a finely divided state obtained from the corresponding metal carbonyls.

4.. The process of producing metallic bodies which comprises arranging a plurality of finelydivided metals which are capable of being sintered to a coherent mass when in such a finelydivided state, in layers adjacent each other, the metal portion of each layer being difierent from the metal portion of its adjacent layer and the metal portion of at least one layer being derived from the carbonyl of that metal, and subjecting the mass to a sintering treatment by the action of heat alone.

5. The process defined in the preceding claim in which at least one of the layers is consolidated to a porous mass by a consolidating treatment 100 prior to being arranged adjacent the other layers.

6. The process of producing metallic bodies which comprises arranging a plurality of finelydivided free metals, which are capable of being sintered to a coherent mass when in such a finelydivided state, in layers adjacent each other, the metal of each layer being diflerent from the metal of its adjacent layer and the metal portion of at least, one layer being derived from the carbonyl of that metal, and subjecting the mass to a sintering treatment by the action of heat alone.

'7. The processof producing metallic bodies which comprises arranging a plurality of finelydivided metals, which are capable of being sintered to a coherent mass when in such a finelydivided state, in layers adjacent each other, the metal portion of each layer being different from the metal portion of its adjacent layer and the metal portion of at least one layer being derived 120 from the carbonyl of that metal, and subjecting the mass to a sintering treatment by the action of heat alone, and then subjecting the sintered material to a mechanical compression moulding treatment.

8. The process of producing metallic bodies which comprises arranging a plurality of finelydivided free metals, which are capable of being sintered to a coherent mass when in such a finelydivided state, in layers adjacent each other, the metal of each layer being different from the metal of its adjacent layer and the metal portion of at least one layer being derived from the carbonyl of that metal and subjecting the mass to a sintering treatment by the action of heat alone, 135 and then subjecting the sintered material-to a mechanical compression moulding treatment.

9. The process of producing metallic bodies which comprises arranging a layer of finely-divided nickel derived from nickel carbonyl adjacent a layer of finely-divided iron from iron carbonyl and sintering the mass by the application of heat alone. v

10. The process of producing metallic bodies which comprises arranging a layer of finely-divided copper adjacent a layer of finely-divided iron from iron carbonyl and sintering the mass by the application ofheat alone.