Diamond-containing Composite Materials Research Articles

Wear Intensity of the Functional Components Made of Diamond-Containing Composite Materials during the Operation of Tools in the Process of Rock Destruction

Wear Intensity of the Functional Components Made of Diamond-Containing Composite Materials during the Operation of Tools in the Process of Rock Destruction

A novel method for in situ TEM measurements of adhesion at the diamond\u2013metal interface

The procedure for in situ TEM measurements of bonding strength (adhesion) between diamond and the metal matrix using a Hysitron PI 95 TEM Picoindenter holder for mechanical tests and Push-to-Pull devices was proposed. For tensile tests, dog-bone shaped lamellae 280–330 nm thick and ~ 2.5 µm long were used as objects of study. The lamellae were manufactured using the focused ion beam technology from the metal–diamond interface of diamond-containing composite material with a single-phase binder made of Fe–Co–Ni alloy. The experimentally determined bonding strength was 110 MPa.

Reduction of cutting tools wear by using new materials in processing

Automation of machine-building equipment, increasing processing speeds and expanding the range of the materials processed necessitated the development of effective abrasive materials that retain the ability to work under extreme conditions. A tool made of diamond-containing composite materials due to the record hardness of diamonds cannot be replaced by any other materials when processing products made of super hard materials, glass, ceramics, natural and synthetic materials. At the present stage of scientific and technical progress strength, viscosity and other characteristics of structural materials are increasing so rapidly that the tool materials available for production in a number of cases do not allow high-performance processing of blanks. Due to these features of modern production, the use of super hard materials is becoming increasingly important in metalworking. Natural (À) and synthetic diamonds (ASO) ASR, ASV, ASK, ASS, A M, ASN are used in industry. A diamond is the hardest material, possessing high red-hardness and wear resistance; there being no adhesion with many materials for diamonds. The disadvantage of diamonds is their fragility. Diamonds are used for the manufacture of diamond tools and fine powders. Other characteristics of construction materials increase so quickly that the tooling materials available for production in some cases do not make it possible to obtain high-performance crystal diamonds used to equip tools. Diamond chisels for thin sharpening and boring of the parts from aluminium alloys, bronzes, composite metals and non-metal materials are most widely used. A diamond instrument is applied for treatment of such hard materials as germanium, silicon, semiconductor materials, ceramics, heat resistant steels and alloys. The quality of the processed surfaces of parts increases with the use of diamond tools. Processing is carried out with the сutting speeds over 1000 m/min. Surface parts processed in these conditions, have low roughness and high accuracy sizes. The article shows that application of superhard materials, acquires still greater value in modern metal-working

СИНТЕЗ КОМПОЗИЦИОННОГО КЕРАМИЧЕСКОГО МАТЕРИАЛА И ИССЛЕДОВАНИЕ ЕГО АБРАЗИВНЫХ СВОЙСТВ

The innovative diamond-containing composite material formed by micro-arc oxidation on the surface of a sintered billet from a diamond-aluminum mixture has been developed. The method of the modification of the basic technology of a material obtaining has been proposed in order to reduce energy consumption and improve its frictional properties. The total time of material formation is reduced by replacing a part of the aluminum powder with white fused abrasive alumina powder, subsequent sintering and formation of diamond-ceramic material by micro-arc oxidation. It was found that the addition of corundum powder has a positive effect on the progress of the microarc oxidation process. A basic structural model of the new material has been developed. Friction tests have shown the advantage of diamond-containing materials of modified composition in comparison with the basic one. It is proposed to use the new material as a tool one for precision abrasive micro-processing of solid materials.

Features of the Structural-Phase State of the Diamond-Matrix Boundary Zone in Diamond-Containing Composite Materials

Preliminary metallization of the diamond component, which promotes the formation of chemical bonds on the diamond-matrix contact during subsequent sintering, is used to increase the strength of diamond retention and the durability of diamond-containing metal matrix composites. There are restrictions on carrying out metallization to create diamond composites with a cemented carbide matrix, since reheating the metallized coating at high sintering temperatures of carbide powders leads to its destruction, diamond graphitization and deterioration of the material properties. The structural-phase state in the diamond-matrix contact zone has been studied and the main factors providing the strength of diamond retention in diamond-cemented carbide composites obtained by hybrid technology that excludes the reheating of the metallized coating have been revealed. It was revealed, that the developed hybrid technology combining the thermal diffusion metallization of diamond and sintering according to the self-dosed impregnation scheme in one cycle ensures the production and preservation of the metallized coating by the methods of scanning electron microscopy, X-ray diffraction and X-ray phase analysis, Raman spectroscopy. Comparative tests have been carried out and it is shown that the specific productivity of experimental samples of a diamond tool (ruling pencils) with a metallized diamond component is on 39% higher than same parameter of pencils without metallization.

The influence of temperature on interaction of Sn–Cu–Co–W binders with diamond in sintering the diamond-containing composite materials

The influence of sintering temperature on interaction of Sn–Cu–Co–W metallic binders with diamond for diamond-containing composite materials has been studied. The powdered components of metallic binders and synthetic diamonds AS150 were mixed with the organic binder and applied on a steel base. Sintering was performed in vacuum at 820–1100°C. It has been found out that in the composite materials, tungsten carbide (WC) is formed at sintering temperatures exceeding 900°C. Catalytic phase transformation of diamonds into graphite under the effect of the liquid phase containing dissolved cobalt and tungsten occurs at the same temperatures.

Influence of the microstructure of a diamond-containing composite material on the tool cutting ability when grinding a diamond single crystal

Using the methods of electronic scanning microstructure and X-ray analysis, the influence of the structure of diamond-containing composite materials on the cutting ability of the tool for circular grinding of diamond single crystals has been studied. It is shown that the use of an oxide-hydroxide glass with a spreading temperature of 570–590 K as a precursor of the binder leads to the formation of melt films on the surface of silicon carbide and diamond particles at 600–630 K and the glass content in the batch is 10 vol. %. The conversion of oxidehydroxide glass films to oxide films proceeds at 700–775 K during the sintering of the composite material. Depending on the volume content of the glass in the charge, the porosity of the compact, three types of structure of composite materials are distinguished: a volumetric skeleton of glass-clad diamond particles and silicon carbide with pores at the sites of multiple compounds; a frame made of glass-clad diamond particles and silicon carbide with glass pores in places of multiple connections; a matrix of glass and the particles of diamond, silicon carbide and pores located in it. The maximum cutting ability of the tool for circular grinding of diamond is provided by a composite material with a structure of the first type.

Design of composites for thermal management: Aluminum reinforced with diamond-containing bimodal particle mixtures

A new design route is proposed in order to fabricate aluminum matrix diamond-containing composite materials with optimized values of thermal conductivity (TC) for thermal management applications. The proper size ratio and proportions of particulate diamond–diamond and diamond–SiC bimodal mixtures are selected based on calculations with predictive schemes, which combine two main issues: (i) the volume fraction of the packed particulate mixtures, and (ii) the influence of different types of particulates (with intrinsically different metal/reinforcement interfacial thermal conductances) on the overall thermal conductivity of the composite material. The calculated results are validated by comparison with measurements on composites fabricated by gas pressure infiltration of aluminum into preforms of selected compositions of particle mixtures. Despite the relatively low quality (low price) of the diamond particles used in this work, outstanding values of TC are encountered: a maximum of 770W/mK for Al/diamond–diamond and values up to 690W/mK for Al/diamond–SiC.

Modelling of the Temperature Field in a Diamond-Containing Composite Material with Organic Matrix

Numerical modelling was used to study the temperature field in a diamond-containing composite material with an organic matrix. An analysis was made of the influence of the thermophysical properties of the binder, and also of the coatings on the diamond grains, on the temperature field in the composite. The results of modelling of a non-stationary temperature field in the diamond tool composite are given.

The effect of technological parameters of intensive electric sintering on the efficiency of inserts produced from diamond-containing composite materials in a cobalt binder

A device and express methods to analyze operating characteristics of diamond-containing composite materials in a cobalt binder have been developed. The experimental studies of the dependence of the diamond-containing composite material tools efficiency on intensive electric sintering have been conducted under the close-to-real operation conditions. Correlation dependences between technological parameters of sintering, microstructure, physico-mechanical properties, and operating characteristics of diamond-containing composite tool materials have been established. The ranges of variations and combinations of technological parameters of sintering, which are most promising in terms of the quality of the resultant materials, have been defined. On the strength of the data obtained an improved technology has been developed of producing segments from diamond-containing composite materials to equip tools with improved operating characteristics to be used in stone working.

Quality rating of a metal matrix-diamondcomposite from its thermal conductivity and electric resistance

The efficiency of hot-pressed diamond-containing composite materials (DCM) for various tool applications is greatly affected by microdefects, namely, the residual porosity of the metal matrix, damaged diamond grains, and imperfect diamond-matrix interfaces. An instrumental evaluation of these microdefects, predetermining the quality of a tool equipped with DCM, is rather difficult due to the small size, the nonstandard shape, and the strong heterogeneity of specimens. Proposed here is an alternative, nondestructive technique of DCM quality rating, which includes the measurement of electric resistance and thermal conductivity of diamond-containing composites and processing the obtained data by the methods of composite mechanics. It exploits the fact that diamond, being a dielectric, possesses an extremely high thermal conductivity, which allows estimating the residual porosity of a sintered metal matrix from the ratio of specific electric resistances, one being measured and another predicted by a theory. These data, in turn, are utilized to predict the thermal conductivity ofDCMwith an imperfect matrix. Matching with experiments, after solving the inverse problem gives the thermal resistance of diamond-matrix interface, which, within the frame work of the given model, simulates the damage of both the diamond grains and their bonds with the matrix. Thus, the numerical rating of quality is given in terms of two dimensionless parameters. The first one, 0 < K < 1, reflects the quality of the sintered metal matrix, whereas the second one, 0 < R <1, is an aggregate measure of the integrity of diamond grains and the perfection degree of composite interfaces. The quite satisfactory agreement observed between the theory and experiment confirms the efficiency of the technique and the reliability of the data obtained.

Evaluation of the quality of composite diamond-containing materials by their electrical and thermal conductivity

The serviceability of hot-pressed diamond-containing composite materials for application in tools depends substantially on the presence of microdefects, in particular, the residual porosity of the metal matrix, damaged diamond grains, and imperfect diamond-matrix interfaces. Experimental investigations of these defects are very difficult due to their small size and nonstandard shape as well as a strong inhomogeneity of the specimens. We propose an alternative technique of the nondestructive testing of the quality of diamond-containing composite materials, which includes measurement of the electrical resistance and thermal conductivity of a diamond-containing composite and analysis of the data obtained by the methods of composite mechanics. The quantitative estimate of quality is given in terms of two dimensionless parameters. The first of them, 0 < K < 1, reflects the quality of a sintered metal matrix, whereas the second, 0 < R < 1, is an aggregate measure of the integrity of diamond grains and the degree of perfection of the interfaces in a composite. The good agreement between theory and experiment corroborates the efficiency of this technique and the accuracy of the presented data.

Structure and Properties of Teflon Composites with Natural Diamond Powders

The results of experimental investigations of the structure and properties of composites based on polytetrafluorethylene (PTFE) containing natural diamond powders (NDP) of different dispersity are presented. To obtain diamond-containing compositions for antifrictional applications, we used a preliminary mechanical treatment of NDP (40 μm) in a planetary mill. It was stated that the formation of the maximum ordered small-spherulite structure of PTFE after injection of NDP significantly increased the wear resistance and deformational and strength characteristics of the polymer composite materials. To produce abrasive materials, PTFE was filled with NDP having a larger graininess (from 40 to 125 μm). It was found that the injection of NDP did not cause evident morphological changes in the binder — the bonds between diamond grains and the polymer are created by physicomechanical forces. To strengthen the adhesion interaction at the interface between the binder and diamond grains and to raise the wear resistance of the material, a complex modification of the polymer with inorganic and organic fillers was carried out. It is shown that the injection of the complex filler significantly improves the tribotechnical and operational properties of the diamond-containing composite material. The general laws of the influence of NDP on the formation of the supermolecular structure of PTFE are revealed. It is shown that, by varying the degree of dispersity and the content of NDP in PTFE, and by applying different methods of their injection into the polymer matrix, it is possible to control the operational properties of the composites and to produce materials of different functional application, from antifrictional to abrasive ones.

Strength of diamond-containing composite material based on tungsten carbide hard alloy

Strength of diamond-containing composite material based on tungsten carbide hard alloy

Optimization of the process of manufacture of diamond-containing composite materials based on titanium carbide-steel alloys

A study was made of the conditions of production of tungsten-free composite materials by sintering in a high-pressure chamber and in vacuum. Good-quality nonporous specimens of titanium carbide-steel materials cannot be produced by hot pressing in graphite dies. The hardness of materials sintered in a HPC is higher (81–86 HRA) than that of materials sintered in vacuum (75–82 HRA.). Heat treatment slightly lowers it (to 77–85 HRA). The highest wear resistance is exhibited by vacuum-sintered materials. In alloys sintered in a HPC a directional orientation of the steel binder with titanium carbide grain inclusions was observed. In service tests the properties of composition diamond-containing materials based on titanium carbide-steel alloys were found to match those of Tvesal alloys-diamond-containing composites based on a tungsten-group hard metal.