Measurement and Quality Control of a Nanomodified Surface Layer of Machine Parts

Research into the possibility of defect structure management, and measurement and quality control of a nanomodified surface layer of machine parts are the key goals of surface engineering. The first part of the problem was previously solved by cavitation technology using nanomodified coolant in turbine blade finishing. An attempt to solve the second part of the problem concerning measurement and quality control of a nanomodified surface of turbine blades has been made in this paper. Surface roughness and microhardness have been controlled while measuring. A methodology for estimating the specific number of microcracks, being an additional parameter for assessing quality of the surface layer of machine parts, has also been developed. Surface roughness was measured using SEYTRONIC PSH8-4 profilograph-profilometer, and microhardness of the sample surface was measured using HMV-G21DT tester. The number of microcracks per unit surface area was estimated using VEGA3 TESCAN scanning electron microscope at 921x magnification. Application of the developed control technique allowed obtaining quantitative assessment of nanomodifiers in surface treatment of machine parts. Experimental research has revealed that due to filling microcracks with chromium nanoparticles using cavitation, and grinding of the part, surface roughness Ra decreases by 11%, surface microhardness increases by 7%, and the specific number of surface microcracks decreases by more than 30%. A comparative analysis of the root-mean-square values of roughness, microhardness, and number of surface microcracks has revealed that using of nanomodified coolant in grinding leads to a decrease in these values by 7%, 10%, and 10%, respectively, which indicates improved repeatability.