IDENTIFICATION OF TECHNOLOGICAL RISKS AND IMPROVEMENT OF QUALITY OF CARBON-CARBON COMPOSITES
It is presented the results of research carried out with the aim of improving the quality of the manufacture of parts from carbon-carbon composites. Used in this case, the production method is based on the impregnation of the frame from carbon fiber liquid coal-tar pitch and a graphitization of the composition. Composite materials obtained by this technology have unique properties, including under high temperatures and loads, but their quality is sensitive to the properties of raw from natural materials. The aim of the work was to ensure the stability of the properties of carbon-carbon materials in the production, in particular by identifying and addressing the factors that increase the risks. The results are based on long-term monitoring of the process and products, including using regression analysis of production data. Direct relationship between certificate data of raw and physico-mechanical properties of the finished product is not determined. The peculiarity of the problem in small-scale production is the availability of only a relatively small sample of data, which limits the possibility of statistical methods. For these conditions there is provided a method of identifying characteristics of the raw material, the totality of which can increase the risk of production of unsuitable products. It was developed the mathematical model of the cumulative influence of properties of raw material on the quality of the product and the dependence for calculation of risk. Before inclusion in the calculation the characteristics of the raw materials were ranked according to the degree of influence on risk assessment. Thus it was selected 4 characteristics from 6 which included in the certificate. It was constructed a linear form, which is a fitting criterion of used coal tar pitch.