THE POLYMER-CERAMIC MATERIAL FOR THE MANUFACTURE OF GAS DISCHARGE CHAMBER FOR THE ELECTRIC ROCKET ENGINE

This study discusses the creation of heat-resistant dielectric composite material based on organosilicon polymers for the manufacture of gas discharge chamber (GDC) for the electric rocket engine (ERE). A binder has been proposed that meets the high requirements for vibration resistance and electromagnetic permeability of GDC in the megahertz range of electromagnetic waves. Based on this binder filled with silicon nitride powder, GRС was designed; this product was fully tested as part of laboratory 200 kW ERE. The research of structural transformations that occur during heating of materials was carried out by synchronous thermal analysis. The material obtained in the result of the experiment, the basis of which was SiSiB®PVMQ filled with Si3N4 60% by mass, is characterized by a number of properties that are structured and described in this study. As a result of the study, it was demonstrated that the studied material is characterized by heat resistance up to 400 ºС. On the basis of these materials, the authors produced a GDC, which was tested as part of a laboratory model. It was established that the increase in mass loss over 400 °C is due to the initiation of the process of thermal degradation of the main polymer chain.

Abrasion resistance of Ni-B/Si3N4 composite layers produced by electroless method

Purpose: The paper presents the results of investigations of Ni-B/Si3N4 composite layers produced on steel substrate by electroless method. Design/methodology/approach: Amorphous silicon nitride powder (Si3N4) with nanometric particle sizes was used as a dispersion phase for the production of composite layers. Ni-B/Si3N4 composite layers were produced in baths of varying Si3N4 powder content. For comparative purposes, the study also includes results related to a Ni-B layer. The Si3N4 powder and the structure of the produced layers were characterized. The topography and morphology of the surface of the produced layers are presented. The adhesion of the layers to the substrate material was determined. Microhardness and tribological properties of test materials were determined. Findings: The results of the studies show that Ni-B/Si3N4 composite layers and Ni-B composite layers are characterized by compact structures and good adhesion to the substrate material. The incorporation of Si3N4 particles into the Ni-B layers increases the degree of surface development of the layers. The Ni-B/Si3N4 composite layer material exhibits less microhardness and less abrasive wear compared to Ni-B layers. However, the extent of wear damage of the Ni-B/Si3N4 is relatively small comparing to Ni-B layers.