Materials Science Forum Vol. 1037

Abstract: The heat-loaded part of the combustion chamber of a liquid rocket engine are Considered. The proposed coating has several layers: an internal metal coating that contacts the part or substrate, and an external coating made of a mixture of ceramic granules and metal powder. At the same time, to obtain the initial surface for coating with the required surface layer roughness, it is proposed to use the method of sand blasting. The article analyzes possible mechanisms of material formation for "base-coating" transition zones, as well as the influence of their chemical composition on the adhesive strength of layers.. The choice of brand and combination of materials used for coating is justified. Technological modes that have been tested in production conditions when applying heat-resistant coatings to parts of modern rocket engines are proposed. The influence of technological parameters of the initial surface preparation process and the geometry of the resulting micro-relief of the substrate on the adhesion characteristics of a multilayer coating made of heat-protective materials operating in the high-temperature zone of the combustion chamber of liquid rocket engines is revealed.

Abstract: The results of studies of wear resistance and tribological properties of experimental single carbide hard alloys grades with modified Co-Mo-Ti binders upon conditions of friction without lubricant on stainless steel are presented. All the data obtained were compared with similar parameters for the basic alloy VK8 (Co-Mo), on the basis of which the experimental grades were developed. Tribological tests were performed on tribometer which implemented a scheme of friction "pin on disk" at constant sliding speed and normal load values with artificially heated tribo contact zone. Studies have found that partial substitution of cobalt in a binder by Mo and Ti has led to a decrease in average friction rates. It was established that the greatest wear resistance and the best tribological characteristics were obtained for specimens of experimental grade 2.22 (5,65%Co+1,8%Mo+0,6%Ti). The process of friction for this pin material was characterized by the formation of secondary structures with high shielding properties, reducing of the adhesive interaction of materials, low volume wear intensity, minimal friction coefficient, as well as the least roughness of friction tracks on the counter body (disk). An increase in the proportion of molybdenum in the binder of more than 5% reduced the wear resistance of the experimental grades in comparison with the basic alloy VK8.

Abstract: The paper presents the results of studies of the profile of the impregnated diamond surface depending on the grain size and initial roughness of the matrix. The experiments were carried out by impregnating powders of different grit size into a matrix made of low-carbon low-alloy steel with HB180 hardness using a ball indenter. The roughness parameters were measured using a contact profilometer. The height and step parameters of roughness and the curve of the profile bearing length were evaluated. In studying the effect of grain size on the surface profile, it was found that the optimal grain size should be 0.5...0.8 of the initial surface mean spacing profile irregularities. The shape of the Abbott-Firestone curve in this case corresponds to a flat profile. Experiments carried out with varying the initial roughness of the samples confirmed the dependence of the optimum grain size on the mean spacing of the profile irregularities. The developed research procedure can be used to design technological processes of hardening parts, tools and accessories by diamond impregnation.

Abstract: The article presents the results of studies of titanium alloy VT20 in ultrafine-grained (UFG), subfine-grained (SMG), fine-grained (MZ) and mesopolycrystalline (MPC) states, obtained, including by methods of plastic deformation and subsequently subjected to ion implantation. The effect of grain size on the structural-phase state of the titanium alloy surface and mechanical properties is shown.

Abstract: The article presents the results of the influence of the structural state of titanium alloys VT1-0 (α-alloy), VT20 (pseudo-α-alloy), VT6 (α + β) -alloy of the martensitic class) and VT15 (pseudo-β-alloy) on the penetration depth ions of nitrogen, aluminum, copper and the cathode of the alloy 50% Cu – 50% Fe. It is shown that the structural class of titanium alloys selected for the study, when exposed to ion implantation by both gases and metals, does not significantly affect the depth of their penetration.

Abstract: A method for determining the residual stress through the deformation of a witness sample during pneumatic blasting of gas turbine engine parts with microbeads is proposed. During the study, the processing modes and the diameter of the microbeads were changed. It is shown that with an increase in the diameter of the micro-ball from 0.3 mm to 0.7 mm, the deformation of the samples increased by 2 times, and with an increase in the speed of their movement from 70 m/s to 90 m/s by 50 %. The mechanism of formation of residual stresses and deformations of the treated surface of the witness sample is proposed.

Abstract: The issues of the process modeling of wear-resistant covers infusion of the NiCrBSi system, strengthened by the addition of solid powder materials are studied in the article. The results of a numerical study of the effect of heat current and thermophysical properties of materials on the process of heating and infusion of the cover are presented. The statements about the advantages of powders based on ZrO2 are demonstrated. Particular attention is paid to the issue of cracking in the cover after infusion. The assumption is substantiated about the positive effect of the addition of ZrO2 powders on the increase in the crack resistance of the cover.

Abstract: The article discusses the possibility of using pulsed laser ablation of nanosecond duration to modify the surface of a cutting tool after regrinding and restoration. Experimental studies of the resistance characteristics of cutting tools with modified surfaces via laser ablation in air and in liquid have been carried out. It was found that after modifying the surface of cutting plates via laser ablation in air, the wear on the trailing surface of the cutting tool at a processing speed of V = 50 m/min is 8 times less than that of the untreated one, the build-up is 20 times less. The wear of the trailing surface of the plates at V = 70 m/min is 2 times less than that of the untreated sample. The resistance studies show surface modification of the cutting tool increases the tool life of the remanufactured tool, overall tool life and savings in tool costs.

Abstract: There are results of studying the parameters of the indenter contact interaction with the surface when processing cylindrical parts made of 45 steel of different hardness by surface plastic deformation (SPD) methods with single-indenter elastic tools (diamond burnishing, ball burnishing). There were considered such characteristics as the resistance force when the indenter starts and in the steady state of SDP, the range of force fluctuations during processing, friction factor when the indenter starts and in the steady state, as well as some derivative coefficients. Adequate physical-statistical models for the quantitative estimation of the contact interaction parameters from SPD processing factors are obtained.

Abstract: Formation of roughness during treatment by polymer-abrasive brushes occurred as a result of interaction of cutting micro-relief with processed surface. The cutting micro-relief of abrasive instrument is described in the form of random process with normal distributional law. When calculation of roughness, the depths of penetration of cutting lugs in processed material as well as regularity of changing of radial radius of rounding of peaks of cutting lugs from modes of treatment are taken into consideration. Set are relations of roughness of processed edge from modes of treatment (deformations of instrument, cutting velocities, feeding) as well as from constituent cutting force. It is proved that usage of polymer-abrasive brushes for rounding of edges faces all requirements of aviation industry on roughness of processed edges.