High precision measurement technique of very small quantities of metallic wear

Starting from experimental modelling of the wear of alloy steel surfaces (moulds, augers, cylinders), at injection of plastics with glass fibres, this paper approaches a very difficult issue both in tribology, and in many other areas of research, namely, gravimetric measurement with high precision of the very small weights of metallic material. Last generation electronic balances have a maximum accuracy of 0.1 mg. In this context, we present an indirect method of measuring weights of less than 10-1 mg, based on the technique of radioactive isotopes. This allows very precise measurement of some weights of the 10-4 mg order. The method involves superficial irradiation with neutrons of the metal samples (ferrous or nonferrous) in a nuclear reactor, together with a standard (a small piece of span, from the same material, weighing the order of 1-2 mg). Wear testing is done on experimental couples with different types of contact: punctual, linear or on the surface, in any friction conditions: dry or lubricated. The metallic wear is collected by taking a sample of lubricant or a sample of washing liquid after testing (in the case of dry friction) and is measured (as counting speed). By comparing the counting speed of the wear of the activated sample and the counting speed of the standard, it can determine with high precision the weight or volume of the harvested wear. By reporting to the testing time, the wear speed of investigated material is obtained with great ease. © 2016, Editura Cefin. All rights reserved.