Influence of the relationship between component compositions on basis of mine and oxide aluminum on heat and electrical engineering, properties and microtility

Abstract

Abstract. Problem  statement. Problematic  issues  in  the  field  of  friction  and  wear  occur  mainly  when used  in  extreme conditions of work parts. It increasingly meets the requirements of metal ceramics. But designers do not always have reference data on the selected metal ceramics. In this work, such properties as hardness, wear resistance and thermal properties of metal-ceramic coating on the basis of copper and aluminum oxide are investigated. (Cu + Al₂O₃). Methodology.. The hardness was evaluated by measuring the microhardness of the PMT-3 device  with a load of 0,2 kg,  the incisions were carried  out in a step  of 0,1 mm.  To determine the microhardness, samples of the type "metallization figure" were made on the standardized modes of the plasma torch. From these specimens, research slabs were made. Wear resistance was estimated by the time, for which the layered coating with a thickness of 1 mm is stitched with abrasive material. The abrasive material is an electroporation of 100…200 microns in diameter, which  was  fed  with  compressed  air  at  a  pressure  of  0,6  MPa.  The  distance  from  the  nozzle  to  the  coating  was  10  mm,  and  the abrasive  costs  6,4∙10-4 kg/s. The  plate  method  was  used  to  determine  the  thermal  conductivity  in  the  temperature  range  of 100…700 °C. For the thermal stability test, the method of alternating heating and sharp cooling of the samples by compressed air jet of the regime wasused: 20…900…20 °C. When measuring the volumetric resistance, an electronic unit of type E6-3 was used, and the electrodility was determined using the AII-70 apparatus. Results.. The hardness of the composite coating Cu + Al₂O₃ increases to 6,6 times withan increase in the percentage of Cu + Al₂O₃ to 90 %. With increasing distance from the surface of the spray coating in depth, the microhardness decreases. In this case, the steepness of the fall for coatings with a higher content of aluminum oxide than for coatings with low potassium content. The durability of the coatings is proportional to the microhardness, with the increase in the percentage  of  copper  in  the  coating,  the  coefficient  of  thermal  conductivity  increases  to  the  thermal  conductivity  of  copper. Fluctuation of the coefficient of thermal conductivity depends on the thickness of the coating. Thermal stability of plasma coatings is maximal when the amount of ceramic (Cu + Al₂O₃) and metal (Cu) components is approximately the same. The same ratio can be used not only in the protective, but  also in the electrical insulation. Scientific novelty. Significantly expanded  information on the technological  properties  of  coatings  based  on  copper  and  ceramics. Practical  significance. The  results  of  the  study can  serve  as reference material for designers and technologists of machine-building enterprises.