INCREASING THE RESISTANCE OF PRECISION INSTRUMENT-MAKING ELEMENTS FROM OPTICAL GLASS TO EXTERNAL THERMO-INFLUENCES BY PRELIMINARY ELECTRON-BEAM PROCESSING OF SURFACES
- 1 Department of Electrotechnical Systems, Cherkassy State Technological University, Ukraine
- 2 Department of Physics, Cherkassy State Technological University, Ukraine
- 3 Faculty of instrument-making, National Technical University of Ukraine "Kiev Polytechnic Institute", Ukraine
- 4 Department of organization of technogenic-prevention work and health safety, Cherkassy Institute of Fire Safety named after Heroes of Chornobyl of National University of Civil Protection of Ukraine , Ukraine
The results of experimental studies to improve the properties of the surface layers of the elements of optical glass (K8, K108, 6 8 2 K208, BK10, TF110) after their processing by mobile electron beam with density of heat exposure F = 7·10 …8·10 W/m and n -3 -2 displacement speed V = 5·10 …5·10 m / s (a reduction of residual microroughness height at the surface from 4 … 6 nm (unprocessed elements) to 0.5 … 1 nm (processed elements), the occurrence of melted layers of thickness up to 250 … 300 microns with a modified structure, which is close to the quartz glass) are presented. It was found that the improvement of these properties increases the resistance of elements to external-heat: an increase in 1.3 … 1.7 times of the critical value of external heat fluxes and the time of their exposure, the excess 5 7 of which leads to the destruction of elements and damage to the test instrument turndown external pressure 10 …10 Pa; increasing the maximum permissible values of thermal stress in the elements from 20 … 40 MPa to 90…100 MPa heating temperatures 300 … 1200 K;an increase of the probability of failure-free operation in the 2 … 2.5 times by increasing the speed of the external heating from 100 K / s to 400 K / s.