TECHNOLOGY OF DEPOSITION OF COATINGS FROM HARD ALLOYS ON THE WORKING SURFACES OF FRICTION UNITS

A technology has been developed for applying explosively to the surface of centrifugal pump parts for pumping overheated distillate under NPP conditions of hard alloy coatings of the CrC-Ti system, which ensures high hardness of the coatings and the strength of their connection with the surface to be coated, and the best tribotechnical materials in comparison with existing materials friction characteristics against siliconized graphite in water.

Development of a method for siliconizing high-density graphite of the MPG grade

Рассмотрен способ силицирования высокоплотного графита марки МПГ; показано, что процесс силицирования протекает на всю глубину заготовки и кремний равномерно распределяется по объему поры, при этом карбид кремния распределяется по поверхности, в то время как кремний остается в остальном объеме поры; исследованы физико-механические характеристики и фазовый состав графита после силицирования; показано, что такой силицированный графит возможно использовать в качестве нагревателей вакуумных печей, а также в химических источников тока. A method of siliconizing high-density graphite of the MPG grade is considered; it is shown that the siliconizing process proceeds to the entire depth of the workpiece and silicon is evenly distributed over the pore volume, while silicon carbide is distributed over the surface, while silicon remains in the rest of the pore volume; investigated the physical and mechanical characteristics and phase composition of graphite after siliconizing; it is shown that such siliconized graphite can be used as heaters for vacuum furnaces, as well as in chemical current sources.

Preparation of Siliconized Graphite by Liquid Silicon Infiltration of Porous Carbon Materials

Siliconized graphite was prepared by liquid silicon infiltration (LSI) of carbon preforms composed of mesocarbon microbeads (MCMBs), petroleum coke and graphite powder as the carbon source with binder of phenolic resin. Effects of the carbon source, binder contents, ball-milling time and moulding pressure on the properties of the porous carbon preforms and the siliconized graphite were investigated. The results showed that the moulding pressure was the main factor influencing the open porosity of the carbon preforms. The carbon preforms with porosity of above 45% could be infiltrated completely with Si, and maximum open porosity of 56% could be reached for the carbon preforms. For the siliconized graphite, high MCMBs contents contributed to high density, while high graphite content led to increased carbon remaining. The densities, open porosities, and the highest bending strength of the siliconized graphite were ranged between 2.90-3.01g·cm-3, less than 1.5%, and 317 MPa, respectively.