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MINISTRY OF EDUCATIONS AND SCIENCES OF UKRAINETHE NATIONAL TECHNICAL UNIVERSITY OF DONETSK
Sb. "Physical metallurgy of black and coloured alloys"
UDK669.018.25:621:771 GRNTI 53.49
RESEARCH OF INFLUENCING OF THE MODE MAKING ON STRUCTURE OF HARD ALLOYS ON THE BASIS OF WC BY METHODS OF QUANTITATIVE METALLOGRAPHY
read. Pashinskiy V.V., Kuzmenko O.S.
In the conditions of modern production the high wearproof for the row of details and wares is required. Lately all more frequent the special materials possessing the proper indexes are used - hard alloys. Eksplutatsionnie properties of the given material are largely conditioned by their structural state which in same queue are the result of different technological operations of receipt and treatment of these materials. A structure is this basic link linking technology of material and his conduct in exploitation, therefore she is one of basic objects of control at production and treatment of materials with the set properties. To set correlation between the structure of material and his properties expressed in a number, it is necessary also in a number to describe a structure (by geometrical and other sizes). Quantitative descriptions of spatial structure can not be defined to neither of the known "direct methods" of supervision of structure. The given descriptions and correlation of them with properties are studied in an insufficient measure. By basic components serving for preparation of alloys of the system carbide of tungsten-cobalt, are monocarbide of tungsten (WC) and cobalt. The explored alloys are made the method of powder-like metallurgy - spekaniya mixtures of powders of the W monocarbide and With at a temperature 1320 - 1480С (depending on composition) in presence a liquid phase. At large concentrations With there is only one phase as hard solution on a basis With. WC - enough hard connection with the high module of resiliency and high temperature of decomposition about 2600С. The connective phase of alloys is the hard solution W and With in Co, built on the type of substitution - introductions. The table of contents of the dissolved elements in Co changes from 1 to 8-10% (on mass) in diphasic alloys. On chemical composition of connective phase maintenance of carbon in alloys has influence: at insufficient maintenance of carbon, the W maintenance rises to 12-18%, changing depending on speed of cooling of alloys. A cobalt phase is less hard, than monocarbide of tungsten (in 4-5 times), at her more low resilient modules and comparatively small temperature of melting (~ 1350С). Физико-mechanical and eksplutatsionnie properties of the diphasic alloys WC-Co rely on many factors major from which are: technology of making, maintenance of connective phase, size of the WC corn, composition of connective phase speed of cooling at spekanii. Properties of diphasic alloys it is possible to vary by application of different technological receptions: the intensifyed grinding of mixtures, the use of the high temperature powders W and WC and etc In many cases it is caused thin changes of such receptions in the structure of alloys [1,2]. One of basic methods of adjusting of durability and wearproof of alloys - change of concentration of connective phase. At identical maintenance of cobalt физико-mechanical and eksplutatsionnie properties of alloys to a great extent are determined by the graininess of carbide phase, mainly by the middle size of the WC corns. Change of the WC sizes (accordingly and thicknesses of areas of cobalt sphere) causes substantial changes of durability, plasticity and viscidity of alloys. Durability, viscidity and wearproof in tungsten hard alloys to a great extent must rely on the character of structure of alloys. There are presently hypotheses about the structure of hard alloys are based on the picture of presence of continuous carbide framework with the inclusion of areas of cobalt (before definite high maintenance of connective phase in alloys) or cobalt matrix with the included corns WC, having the large or less degree of contact. As credible a model as the two is also considered, penetrable one in one frameworks [2]. For research standard standards were used, from hard alloys baked under constraint and exposed to additional spekaniyu on the same mode, but without pressure measuring 5х5х30 mm3. On them makroshlifi were made and got the photographic pictures of the explored structures. Then these pictures were processed by the specialized program of computer analysis of the "Image Tool images" in the mode of semi-automatic analysis. For computer treatment the pictures measuring 300*400 pixels were taken. Before the analysis on pictures preliminary count up the quantity of corns and determine a scale after enter these values and conduct scanning of images in the semi-automatic mode. On results the conducted measuring influence of the mode of making on quantitative descriptions was analysed. For research the standards were taken from alloys with maintenance of copula 15% (mass), different by the size of carbide phase. Standards 1, 3, 4, 6 - were prepared from the carbide of tungsten with middle one measuring corns 5,0 mkm; standards 2 and 5 - with middle measuring 15,0mkm. Thus 1,2,3 - the standards baked under constraint; 4, 5, 6 - baked without pressure additionally. After computer treatment the images got statistical descriptions: number of corns of carbide, number of areas of communication, tie-up of particles of carbide and others.
More detailed description is resulted in the Russian language
http://www.rttn.ru/ - patent on hard alloys
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