Key Engineering Materials Vol. 839

Abstract: The paper presents research into heat and mass transfer in agglomerated particles exposed to the thermal plasma flow. The dynamic motion, heating and melting are considered for agglomerated particles. It is shown that the surface temperature of porous particles rather rapidly reaches the value of T_sur>T_melt starting from the area of their introduction into the plasma flow. This effect is determined by the low conductivity of porous particles and indicates to a great temperature difference between the particle surface and its nucleus. It is shown that hollow particles can be obtained from silica sand treated by thermal plasma at 6700 K and 515 m/s velocity. The particle surface displays no clear defects. According to the analysis of X-ray diffraction patterns, the obtained hollow particles have no diffraction peaks.

Abstract: The paper considers the existing problems of the production of ceramic products in the territory of the Russian Federation, presents the priority directions of development of this industry. The study includes the determination of the properties of samples based on the raw material base of the Orenburg region, namely, waste generated during the development of brown coal from the Tyulgansk deposit - white and red clays and nickel slag of OJSC Yuzhuralnickel Combine of the Orenburg region. The study presents data from the study of the technological properties of the raw materials, the development of the composition of the ceramic mixture. The influence of the material composition of the clay / slag mixture on the physic mechanical characteristics of the products of the experimental compositions was determined: compressive strength, fire shrinkage, water absorption and density.

Abstract: Stress-strain curve construction for low-plastic alloys under severe plastic deformation conditions is considered. A material under investigation is cast bronze Cu85-Pb5-Sn5-Zn5. Experiments on upsetting and deep rolling were conducted. Based on these data, the initial hardening modular and the hardening modular at large strain were evaluated. Classic tests on determining an initial segment of stress-strain curve can lead to grate mistakes because shear band sliding can diminishes appreciably both yield stress and hardening modular. A correct methodology for stress-strain curve construction is proposed.

Abstract: This work is devoted to research of the structural-phase condition and changes in the mechano-tribological properties of 0.3C-1Cr-1Mn-1Si-Fe structural steel after plasma electrolytic cementation. Using metallographic and X-ray analysis, mechano-tribological tests, it was found that 0.3C-1Cr-1Mn-1Si-Fe steel in the initial state belongs to the ferritic-pearlitic class, which contains ~ 65% of pearlite grain and 35% of ferrite grain. When samples of 30HGSA steel are saturated with carbon, a modified surface layer with a thickness of 25μm is formed on the surface of the studied samples, including α-Fe ferrite, cementite Fe₃C, iron Fe₃C₂ carbide and an alloying element. It was established that the intensity of wear of the samples after modifying decreased by 2 times, and the surface microhardness after cementation increased 3 times, depending on the original sample.