The article describes the results of experimental studies for the effect of thermal treatment (TTM) of G-X300CrMo27-1 high-chromium cast iron samples in the solid–liquid and liquid state on the structure, phase composition, and properties of ingots. For ingots with a carbon content of 2.8 to 4.5 wt%, cooled at a rate of 3.3 * 10⁻² deg s⁻¹, the dependencies of the structure, phase composition, composition of primary, eutectic carbides and matrix, hardness HV and microhardness of its individual phases and resistance to abrasive wear from the temperature of isothermal holding at TTM. A significant effect of the TTM temperature of melts on the structure and properties of high-chromium cast iron ingots was detected. The temperatures of inflection on the plotted curves for the characteristics of the structure and properties of the ingots were associated with a phase transition in iron at 1400 °C and with a point on the phase diagram liquidus of the Fe-Cr system. This as well as an increase in the concentration of chromium in the composition of primary carbides with an increase in the TTM temperature up to 1480 °C, made it possible to assume that (Cr, Fe)₇C₃ clusters stable in composition were formed in the melt of such cast irons below ∼1500 °C. The reasons for the decrease in the size of primary carbides during G-X300CrMo27-1 molten chromium iron overheating above 1500 °C were substantiated based on these data. During the TTM of fine-crystalline ingots made of hypereutectic cast iron in the temperature range between the liquidus and solidus lines, it was detected that the primary carbides (Cr, Fe)₇C₃ recrystallized resulting in a significant decrease in the chromium content and an increase in the iron content in them. At the same time, their sizes did not change significantly. Their share increased, and the share of eutectic carbides decreased. Such a process also had a significant impact on the properties of the resulting ingots. The most preferable temperatures of hot metal cast irons in the liquid and solid–liquid states were identified based on the results of the studies.

The possibility of using microsilica in the production of mullite–silica refractories was assessed. The chemical and mineralogical compositions of the raw materials, refractory Arkalyk clay and microsilica, were studied. It has been found that primary mullite and quartz formation occurs due to dehydration of kaolinite with the formation of intermediate metakaolinite. The introduction of alumina and microsilica into the charge composition promotes the formation of secondary mullite due to the interaction of aluminum oxide and highly dispersed chemically active microsilica. Free silica in compositions undergoes polymorphic transformations with the formation of cristobalite and tridymite. Mullite–silica refractories with an open porosity of 21%, a compressive strength of 42 MPa, and a thermal deformation temperature under the load of 0.2 MPa–1350 °C were obtained.

The article presents experimental data on the changes in the structural parameters and properties of castings from high-chromium cast iron G-X300CrMo27-1 depending on the carbon content, which ranged from 2.8 to 4.5 wt. %. Castings were obtained under cooling conditions with two cooling rates—0.083–0.117 °C/s and 4.67–5 °C/s. Changes in the structure and properties of these castings after destabilizing annealing and subcritical heat treatment were assessed. Changes in carbon concentration and cooling rate in the crystallization interval have a significant effect on the sizes of primary carbides (Cr, Fe)₇C₃, and on the fraction of eutectic carbides. The microprobe analysis results indicating the effects of cooling rate on the composition of phases in cast iron castings with carbon contents of 4.2 wt. % are presented. The offset value of the crystallization onset temperature and eutectic point with an increase in the cast iron melt cooling rate from 0.083 to 0.83 °C/s is shown. The changes found in the properties of castings with increases in carbon concentration and cooling rate cannot be unambiguously explained by the transformation of the structure of primary and eutectic carbides and changes in the elemental composition of phases. The composition and condition of the matrix has a significant effect on the hardness, bending strength and abrasion resistance of castings. It is suggested that internal stresses arising in primary and eutectic carbides affect the properties of castings in the cast and heat-treated state.

Article considers the influence of additions of rare earth elements such as Sm, La, Ce, Nd, and Y on the structure and properties of hypereutectic high-chromium white cast iron of grade G-X300CrMo27-2. To obtain an increased content of carbides in the studied cast iron samples, the carbon content was 3.75–3.9 and 4.1–4.2 wt%. The amount of rare earth elements additives added to the melt is 0.2% by weight. Data were obtained on the effect of overheating and cooling rate in the crystallization interval on the effect of rare earth additives, the structure and properties of white cast iron castings are given. According to the results of the microprobe analysis, it was shown that, under the chosen crystallization conditions, Sm, La, and Ce can form solid solutions with primary and eutectic carbides (FeCr)₇C₃. La and Ce form solid solutions with austenite. Nd and Y do not dissolve in iron chromium phases. All listed rare earth elements form phosphides and oxyphosphides. Experimental data are presented on the effect of rare earth elements on the size of primary (FeCr)₇C₃ carbides and a hypothesis is proposed on the effect of rare earth elements on the crystallization process of hypereutectic chromium white cast irons. Experimental data are presented on the effect of REE additives on the microhardness of phases, hardness, strength, and resistance to abrasive wear of cast iron castings. It was found that the introduction of these additives into hypereutectic chromium white cast iron does not contribute to the modification of the structure and leads to an increase in the size of primary crystals, as well as a decrease in their mechanical properties. However, the addition of Y increases the abrasive wear resistance, but reduces the strength of castings made from such white cast iron.

The article presents the results of a study of the interaction of titanium melt with of zirconates BaZrO₃ and SrZrO₃, as well as titanate SrTiO₃ under vacuum conditions and in an inert atmosphere at normal pressure. An original titanium heating method was used during the experiments. It eliminated the melt circulation at the interface between the solid and liquid phases. The method was based on resistive electrical heating of a Grade 2 titanium alloy rod or strip pressed into BaZrO₃, SrZrO₃ and SrTiO₃ powders. Studied the structure, elemental, and phase composition of the products formed during various (up to 300 s) contact of titanium melt with surface zirconates and titaniums. The phase composition was compared with the products obtained by heating compacts from a mixture of titanium powders with BaZrO₃, SrZrO₃ and SrTiO₃ powders. It was shown based on the results obtained that titanium, upon contact with these ceramic materials dissolves zirconium and oxygen and reduces barium and strontium to a metallic state. Barium and strontium evaporated due to the high vapor pressure at the experimental temperature, and caused the melt to splash or form a vapor layer that reduced the interaction rate of the melt with the ceramic. When a titanium melt interacted with BaZrO₃ and SrZrO₃ intermediate phases were not formed in quantities sufficient for their identification. The Sr₃Zr₂O₇ phase was formed in small quantities during heating a mixture of Ti+SrZrO₃ powders. When a titanium melt interacted with SrTiO₃, a layer of an intermediate phase was formed, similar in composition to TiO₂. Equations for the chemical reaction of the interaction of titanium with the indicated zirconates and titanate were compiled based on the experimental data obtained. It has been shown that titanium melt weted the surface of BaZrO₃, SrZrO₃ powders well and poorly weted the surface of SrTiO₃ powder.

This study presents the results of a study of the reaction interaction and contact angle during contact between a titanium melt and a calcium metatitanate substrate. It is shown that at temperatures slightly above the melting point, the titanium melt poorly wets the CaTiO₃ substrate surface. The contact angle and the onset temperature of active reaction vary depending on the fractional composition of the CaTiO₃ powders from which the substrates are made and their porosity. Under isothermal holding conditions below the onset temperature of active reaction, the contact angle changes insignificantly. At the onset temperature of the reaction interaction, after a short stabilization period of the contact angle, the reaction leads to rapid penetration of the molten droplet into the depth of the CaTiO₃ substrate and, in some cases, to the expulsion of a Ca-Ti-O liquid phase from the reaction zone. The interaction of titanium melt with calcium titanate is accompanied by a series of physicochemical reactions associated with the reaction interaction, which intensifies with increasing temperature and causes the restoration of calcium to a metallic state and the dissolution of oxygen in the titanium melt, as well as the formation of a liquid Ca-Ti-O layer in the transition zone.