I. E. Kalashnikov

Modification of cast aluminum-matrix composite materials by refractory nanoparticles

The effect of SiO2 and Al2O3 oxide ceramic nanoparticles on the solidification of model samples based on a commercial D16 alloy is studied. The composite samples are fabricated by reaction casting when titanium, nickel, and ceramic powders are mixed with an aluminum melt. The grain size in a matrix, the size and shape of Al3Ti intermetallic inclusions, and the interphase distances in eutectics are determined with optical and scanning electron microscopes. A certain modifying effect of oxide ceramic nanoparticles on the structure of model CMs during their in situ formation is detected, and the inoculation effect of SiO2 added to a melt on the reaction products is most pronounced.

Tribological characteristics of cast aluminum-matrix composites modified by nanosized refractory powders

The results of studying aluminum-matrix composite materials (CMs) reinforced ex situ by disperse nanosize powders obtained by plasma-chemical synthesis, as well as by intermetallic phases formed by in situ reactions, are presented. The structure and tribological properties of aluminum-matrix CMs have been examined. The effect that the manufacturing modes, nature, and size of reinforcing particles have on the structure, wear resistance, coefficient of friction, and stability factors has been discussed.

Aluminum-matrix composite materials with shungite rock fillers

A method is proposed for the introduction of shungite rocks into aluminum melts by mechanical mixing with carriers, namely, aluminum granules and reactive titanium powders taking part in exothermic in situ reactions. The structures of composite materials with shungite rock additions are studied, and a stabilizing effect of these additions on dry sliding friction is revealed.

Local Elastic Moduli of Particle-Filled B83 Babbitt-Based Composite Materials Prepared by Powder Metallurgy Techniques

We have measured local elastic moduli of particle-filled B83 babbitt-matrix composite materials produced by powder metallurgy techniques and containing silicon carbide (SiC) ceramic and modified shungite rock particles as fillers. The measurements were made by an optoacoustic laser method, whose basic principle is to determine the phase velocities of thermo-optically excited longitudinal and shear ultrasonic waves. The addition of 3 wt % of high-modulus SiC particles tends to increase the Young’s and shear moduli (by 10–12%) and decrease Poisson’s ratio (by 5%) relative to a hot-pressed B83 babbitt sample without fillers.

Production of antifriction composite filler rods based on babbit B83 by extrusion

The manufacturing technology of the composite filler rods based on babbit B83 by extrusion is developed. The filler rods have a uniform distribution of the high-strength reinforcing particles (silicon carbide) and the modified rock shungite. It is shown that the hardness and density values of the composite filler rods correspond to the properties of cast babbit B83 alloy, but their wear resistance is superior by a factor of two.

Wear products that form during tribological tests of aluminum-matrix composite materials

The wear products and the friction surfaces of the composite materials fabricated by reactive casting after the addition of commercial-purity aluminum AD1, titanium and nickel powders, and nanosized modifiers to a matrix melt are studied. The dispersity and the chemical composition of the wear products that form an intermediate layer between the contacting surfaces are analyzed, and the dominating wear mechanisms under experimental tribological loading conditions are determined. It is shown that the formation of such a disperse intermediate layer during lubricant-free friction of the synthesized composite materials decreases the temperature in the tribological contact and ensures a transition from weak to intense wear at higher critical loads.

Development and testing of Al-SiC and Al-TiC composite materials for application in friction units of oil-production equipment

The results of laboratory and development wear tests of Al-based composite materials reinforced with TiC or SiC particles under dry sliding friction conditions are presented. It is shown that composite materials reinforced with TiC have better tribotechnical properties (friction coefficient, wear rate, wear coefficient, stability coefficient) as well as wear resistance. On the basis of the friction surface and wear debris investigations, the mechanisms of wear of the composite materials are determined.

Effect of refractory nanoparticles on the structural modification of metal-matrix composites

The structure and tribological behavior of composite materials (CMs) filed by dispersed particles and based on aluminum alloys grown by reactive casting with titanium microparticles and SiC nanoparticles or synthetic diamond mixed to the melt have been studied. The composition, size, and volume fraction of the strengthening phases are determined by optical microscopy and x-ray diffraction. The hardness of the CMs is measured. The tribological properties of the CMs are tested during dry friction on a rider made of grade 45 steel. Alloying nanoparticles are shown to affect the morphology, volume fraction, and sizes of the strengthening phases formed in the CMs. The main phases in the CMs are intermetallic compounds Al3Ti, Al24Ti9, and AlTi. The introduction of SiC nanoparticles in a CM causes the formation of TiSi2 (<1%) particles, whereas TiC carbides (<1%) form in a CM containing diamond nanoparticles. CM-steel friction interaction causes the formation of intermediate layers consisting of mechanical mixtures with an ultrafine-grained structure between the sliding surfaces. Their effect on the stable-friction range is discussed.

Tribological properties of the babbit B83–based composite materials fabricated by powder metallurgy

Technological processes are developed to fabricate composite materials based on B83 babbit using hot pressing of a mixture of powders in the presence of a liquid phase. As a result, the structure of the matrix B83 alloy is dispersed, the morphology of intermetallic phases is changed, and reinforcing micro- and nanosized fillers are introduced and uniformly distributed in the matrix. The tribological properties of the synthesized materials are studied. The friction of the B83 babbit + 0.5 wt % MSR + 3 wt % SiC (MSR is modified schungite rock) composite material at high loads is characterized by an increase in the stability coefficient, and the wear resistance of the material increases by a factor of 1.8 as compared to the as-cast alloy at comparable friction coefficients.

Nanostructuring of dispersion-reinforced aluminum-matrix composite materials

We studied the effect of reinforcing phases introduced into the melt ex situ and formed directly in situ during mechanical activation of powders or mechanical mixing in the melt on the structure and mechanical and tribological properties of aluminum-matrix cast and aluminum-powder composites. Intermetallic inclusions, Al2O3, TiC, SiC, and refractory nanoscale particles served as reinforcing agents.