T. V. Mosina

TiN – AlN-Based Hot-Pressed Composites. Part 1. Structure and Properties

Results of a study into the structure and mechanical properties of a hot-pressed TiN – AlN ceramic with the concentration of AlN in it varying from 0 to 100% are given. Composite materials with a strength of 750 MPa, a crack resistance of 4.4 MPa · m1/2, and a hardness of 13 – 15 GPa measured over a wide range of the indenter load (50 – 100 N) are prepared. These materials exhibit an extremely high resistance to fracture under localized load. The TiN – AlN-based materials are promising for use in tribo-engineering applications — such as ceramic bearings and wear-resistant friction couples.

Metal Surface Finishing With Magnetic Abrasive Powder Based on Iron With Ceramic Refractory Compounds (Mechanical Mixtures)

Magnetic abrasive powders are studied, prepared by mechanical mixing of starting components in the presence of surfactants and adhesive materials. It is shown that with respect to operating properties the abrasive powders prepared are on a par with known powders prepared by spraying, sintering, grinding, and other known methods.

Electric-Spark Alloying of Composite Material of the Systems TiN–AlN and TiN–AlN–(Ni–Cr) as a Method for Applying Wear-Resistant Coatings

Electric-spark alloying is studied for standard tungsten hard alloy VK-8 using developed composite materials TiN–AlN and TiN–AlN–(Ni–Cr) as an electrode. The effect of metallic Ni–Cr-binder within electrode material of the system TiN–AlN on structure and properties of electric-spark coatings on standard tungsten hard alloy VK-8 is studied.

Dependence of the Cutting and Polishing Ability of Magnetic-Abrasive Powders on the Form and Structure of the Particles

It is shown that fragmented particles are preferable to spherical particles for magnetic-abrasive finishing. The cutting elements of such powders are microscopic projections that determine the roughness of the finished surfaces. For a given volume of magnetic-abrasive powder, a decrease in the diameter of the particles increases the number of cutting centers. To maximize metal removal over the duration of the polishing operation and shorten the amount of time needed to reach the minimum value of Ra, it is necessary to use progressively finer abrasive powders as Ra decreases during polishing.

Studies of the physico-mechanical properties of modifiers used to treat iron-carbon alloys

Results are presented from the rolling of complex composite modifiers (CCMs) from powdered materials, including fluxing additives. The main mechanical properties of rolled products made of the CCMs are determined along with the technological parameters that characterize their production and use.

Ceramic particles for the magneto-abrasive treatment of metallic surfaces

It is shown that a uniform distribution of the abrasive component in the matrix of the granules of magneto- abrasive materials (MAMs) gives these materials good cutting and polishing ability. The durability of MAMs in which the abrasive component is secured in the matrix by friction, adhesives, and surfactants is determined by the rate of wear and the adhesive interaction between the initial components. The adhesive-, friction-, and surfactant-bonded magneto-abrasive powders proposed in this article can compete with the magneto-abrasive powders made by established methods.

Frictional properties of TiN - AlN-based hot-pressed composites

The tribological properties of TiN – AlN-based composites forming a friction couple with 65G-grade steel under lubricant-free conditions are studied in the speed range of 4–16 m/sec and pressure of 0.5 – 2.0 MPa. The increase both in speed and load causes a decrease in the coefficient of friction. For a speed of 16 m/sec and pressure of 2.0 MPa, the coefficient of friction is 0.16 – 0.11, and the linear wear is 6.0 – 5.7 μm/km. The superior tribological properties of TiN – AlN composites are related to the high mechanical properties of these materials. During friction at high speeds and loads, the abrasive and adhesive wear decreases owing to the oxide films that form on the surface and play the role of a solid lubricant and thus reduce friction loss.