V. A. Maslyuk

PRODUCTION, MECHANICAL AND TRIBOLOGICAL PROPERTIES OF LAYERED COMPOSITE MATERIALS BASED ON A CHROMIUM CARBIDE ALLOY

Layered materials have been produced by joining hard surface layers of chromium carbide alloys to a less expensive substrate of steel. This method provides a substantial increase in the hardness and tribological properties of the composites, economizes on the use of expensive refractory materials, and decreases manufacturing costs. Composite layered materials of chromium carbide alloys can be recommended for the production of components which in addition to frictional wear are exposed to corrosive media and high temperatures.

Tribological Properties of Hard Alloys Based on Chromium Carbide

Hard alloys of the type KKhN and KKhNF were studied and shown to have low coefficient of friction (f = 0.21-0.17) and wear rate (I = 5.7-7.0 μm/km) at sliding velocity 15 m/sec and load 7 MPa, which make them promising for use as antifrictional materials in dry friction units under load. Oxide films formed at the surface of the hard alloys play the role of solid lubricants and decrease frictional losses.

Structure Formation in Alloys of the Cr3C2–TiN System and the Properties of Materials Based on Them

The addition of 10-20% TiN to chromium carbide made it possible to obtain almost pore-free Cr3C2–TiN alloy specimens by hot pressing in the range from 1500 to 1850°C at a pressure of 35.7 MPa for 25 min. The 90% Cr3C2–10% TiN alloy had the maximum hardness (89 HRA) while the alloy containing 15% TiN had the maximum bending strength (480 MPa). Activation of solid-phase sintering is shown to cause a Cr3C2 solid solution to form in the titanium nitride. In alloys containing 50% or more TiN sintering is activated by the formation of a liquid phase based on the Ti–Cr–C–N eutectic.

Layered Powder Metallurgy Wear- and Corrosion-Resistant Materials for Tool and Tribological Applications. Structure and Properties

Three-layered non-tungsten hard alloys for tool applications of the type KKhNFT5 ― KKhNFT25 ― KKhNFT5 and layered powder metallurgy materials for tribological applications with a working layer of composites based on stainless steels were investigated. Basic requirements for the creation of wear- and corrosion-resistant powder metallurgy materials for tool and tribological applications were formulated. These mainly concern their composition and structure.

Structure and Properties of Iron–High-Carbon Ferrochrome Powder Composites

The physical and process properties of ferrochrome powder produced by grinding of lump high-carbon ferrochrome FKh800 are examined. It is found that the ferrochrome is pulverized sufficiently well, and its physical and process properties allow its use to make wear-resistant powder materials. The effect of ferrochrome content on the structure and properties of materials sintered in vacuum from iron powder compacts and powdered FKh800 is studied. The materials containing 30 wt.% FKh800 are found to have high density, bending strength, hardness, and resistance to abrasive wear.

Sintered Composites Based on Stainless Steel

The effect of the amount of chromium carbide addition on the properties of composites based on stainless steel of the austenitic class and their structure formation during sintering in a vacuum are studied. Compositions with 10, 15, 20, 25, and 30% Cr3C2 and also a content of 5% MoSi2 addition are investigated. It is established that an increase in Cr3C2 content from 10 to 30% for all composites leads to an increase in hardness and wear resistance, but to some reduction in strength, and in some case a reduction in corrosion resistance.

Hard powder alloys and carburized chromium steels in the Cr–Fe–C system

The literature data for the Cr-Fe-C system are used to construct the Fe–Cr3C2 vertical section showing wide two-phase (αFe) + (Cr, Fe)7C3 and (γFe) + (Cr, Fe)7C3 regions. Sintering of a powder mixture of iron and chromium steels Kh17N2 and Kh13M2 with higher chromium carbide is studied, and sintering conditions are optimized. It is shown that dissolution of Cr3C2 in the metal matrix of both chromium steels is described with a series of phase transformations: Cr3C2 → → Cr7C3 → (Cr, Fe)7C3 → (Cr, Fe)23C6. The effect of structure and phase composition on the mechanical properties (bending strength, HRA hardness, impact strength, fracture toughness), tribotechnical characteristics, wear resistance, and corrosion resistance is examined for the hard alloys and carburized steels Fe–Cr3C2, Kh17N2–Cr3C2, and Kh13M2–Cr3C2. Application of the materials developed allows an increase in the service life by 7–10 times for operating elements of feed mills and high-wear parts of equipment in construction industry.

Physical, Technological, and Magnetic Properties of Powder Iron-Nickel Alloys

Methods for the production of 36N, 78N, and 79NM iron-nickel powders have been investigated along with the technological and physical and chemical properties of those powders. Coreduction of the initial oxides was shown to be the most simple, cost-effective, and accessible method.

The Effect of Chromium Steels and Nickel Boride Additives on the Structure and Properties of Iron–High-Carbon Ferrochrome FKh800 Powder Composites

Production conditions, physical, mechanical and tribotechnical properties of iron–high-carbon ferrochrome FKh800 materials alloyed with additives of chromium steels Kh13M2, Kh17N2, and Ni3B are investigated. It is established that a sintering temperature of 1250°C and isothermal holding for 60 min are the optimal parameters for producing such materials. It is revealed that adding steels Kh13M2 and Kh17N2 to the charge changes the structure of materials from two-phase to multi-phase, increases their wear resistance in dry friction against ShKh15 steel counterface by a factor of 2–2.5, somewhat increases their hardness, and decreases their bending strength).

Production and properties of soft-magnetic dielectric materials based on nanocrystalline Fe73Si15B7.2Cu1Nb3 alloy powder

Powder metallurgy methods are used to produce soft magnetic compact materials from amorphous and nanocrystalline alloys. Toroid-shaped samples are warm-pressed from nanocrystalline Fe73Si15B7.2Cu1Nb3 alloy powders and SFP-012A resin binder. The method does not require additional thermal treatment and the samples are ready to use. The key influence on the properties of soft magnetic powder materials is produced by ferromagnetic filling factor (FFF). The optimal experimental conditions to make samples with the minimum porosity and maximum FFF are determined. The density of the samples depending on compaction parameters and resin content is established.