Properties of materials based on silicon carbide

Abstract

Research has been done on the microstructure, lattice parameters, and tribological characteristics of materials based on silicon carbide. It has been found that the most promising material from the viewpoint of tribology is silicon carbide made with phenol binding agent.Recently, ceramics have been widely recognized as a new class of advanced materials with a high level and unique combination of physicomechanical characteristics, which differ favorably from metals and alloys [1]. The strong ceramic based on silicon carbide is a promising tribological material, since it has good mechanical and thermophysical properties, as well as stable hardness and strength over a wide temperature range [2, pp. 108 -128]. Materials based on SiC are used in the aerospace, defense, metallurgical, and general engineering industries, as well as in chemical engineering and medical technology [3]. At the Technology ONPP, research has been done on the general and physicomechanical properties of components made from reaction-bonded silicon carbide after tribological tests [4].To perform the tests whose results are given here, blanks were prepared by semidry pressing with initial density 2.05 g/cm 3 . After pressing the blanks were annealed in a cover of wood charcoal, which reduced the carbon loss, and correspondingly produced reactive sintering with a lower free silicon content. The maximum preliminary firing temperature was 900EC with a rate of increase of 250EC/h, hold time at maximum temperature 3 h.A pyramid of blanks was laid out on a support of silicon carbide covered by carbon fibers for siliciding. At the top of the pyramid there was a crucible containing silicon carbide with a silicon content constituting 0.7 of the blank mass. The maximum siliciding temperature was 1615°C with a rate of increase of 400°C/h and a hold at the maximum temperature of 1.5 h. Five specimens (Nos. 1 -5) were used in examining the general and physicomechanical properties. Specimen No. 1 had a basic charge composition: a mixture of SiC powder, carbon black, and starch binder, with the specimen covered by a diamond-type layer. The other specimens differed from No. 1 as follows: in No. 2, the charge was doped with boron compounds; specimen No. 3 was made with a phenol binding agent; No. 4 additionally contained nanodiamonds in the charge; and No. 5 additionally had nanopowder of finely divided technical carbon in the charge.The apparent density and open porosity were determined by water uptake: the mass of a dry specimen was determined by weighing in air, while the pore volume was determined by weighing a specimen saturated with water; and the specimen volume was determined by hydrostatic weighing. The Vickers microhardness was determined with a PMT-3M instrument. The method was based on indentation with a diamond tip in the form of a regular four-faced pyramid under a load applied for a certain time, with measurement of the diagonals on the indent remaining after relieving the load. Table 1 gives the physicomechanical properties of the specimens.In the...

Prospects of application of nanostructured heterophase polyfunctional composite materials in aero-engine manufacturing

“…П. И. Баранова» совместно с ООО «Диапром» разработаны инновационные технологии. Такие технологии позволяют управлять коэффициентами трения, теп-лопроводности, электропроводностью и прочностью создаваемых материалов [4].…”