Accelerated testing of the friction pairs of mechanical seals made of composite material of the TiC – SiC system

Abstract

Novel wear-resistant materials used in friction pairs are being developed to increase their reliability and failure-free performance in operation, reduce the environmental load and energy consumption in manufacturing processes. One of the promising functional materials for manufacturing durable and wear-resistant parts and products that undergo intensive wear in operation is a powder material of the TiC – SiC system obtained by spark plasma sintering (SPS). SPS is an energy-efficient alternative to hot pressing and environmentally-friendly procedure compared to that used in manufacturing serial friction pairs from the lead-graphite composition NAMI GS-TAF-40 for tractor industry. Prototype friction pairs made of the powder material of the TiC – SiC system have been manufactured by SPS technology using sketches of a serial friction pair of the mechanical seal of a centrifugal pump 16-08-140SP of the cooling system of D-180 diesel engine developed for a T10 tractor. The goal of the study is accelerated bench testing of the obtained experimental friction pairs. The tests were carried out on the equipment of a modular block for testing mechanical seals designed for the USI «Climate». The method of accelerated testing provided simulation of the operational tests of experimental friction pairs of mechanical seals of centrifugal pumps of the cooling system of an internal combustion engine with a 2.0 – 2.5-fold acceleration. The criterion for the applicability and evaluation of the results of accelerated tests of experimental friction pairs was the similarity of temperature conditions of the water pump seal and the compression forces of the rings in the friction pair under real diesel operation and the accelerated test modes for the increased rotational speed of the centrifugal water pump shaft. A path traveled by the point of the average radius of the «contact line of touch» of the working surfaces of the rings with allowance for test acceleration coefficient (2.0 – 2.5) was taken as a basis for assessing the reliability and durability of test objects. During accelerated testing, all the test parameters were taken into account in addition to visual inspection of the test equipment and the mechanical seal. The wear resistance of the experimental friction pairs was determined by change in the mass through intermediate measurements of the ring wear after 100 and 200 hours of testing. Accelerated bench tests revealed that a friction pair with parts made of a TiC – SiC-based composite material will provide at least 1.5- fold increase in the service life of the mechanical seal of the centrifugal pump of a D180 diesel cooling system.