Ultra-Thin Layer Activation as a Potential Tool for Nano-wear Characteriation
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1085-T05-16
Ultra-Thin Layer Activation as a Potential Tool for Nano-wear Characteriation Liviu Popa-Simil R&D, LAVM LLC., Los Alamos, NM, 87544 ABSTRACT The ultra thin layer activation techniques (UTLA) is an application mainly of the recoil nuclear reaction that generates radioactive ion beams used for MEMS and fine machinery parts radioactive labeling. The UTLA method relies on creation of a very thin nano-layer on the technologic surface that to exhibit radioactivity due to implanted radioisotopes. For current material loss applications the tracers concentration is of the order of ppb of different material generated by nuclear reactions induced by ion beam bombardment. This layer offers plenty of gamma or X rays easily detected over the natural background level, directly by a radiation gauge placed above the entire functional mechanism, or by measuring the radioactivity of the labeled particulates accumulating in a closed loop lubricant or fluid. In the case of MEMS devices the material concentrations are required to be high enough in order to produce a good radioactive signal or the use of sensitive methods to detect the isotopic materials lost from the labeled technologic surfaces. There are various possibilities of applying tracer materials on the MEMS devices in order to determine the material loss and to correlate it to the operation regime. INTRODUCTION The use of radioisotopes to track the wear of the tribologic devices dates since late 1940th [1] debuting with the usage of neutron irradiation to label the material of the mechanical part. The 1950th were the years on vogue for the neutron labeling technology [2]. The procedure relied on the exposure of the entire mechanical part to neutron irradiation inside a nuclear reactor. The drawback was the fact that the entire part was irradiated and to obtain a reasonable detection sensitivity for the so called “tribologic interest material”, that layer of material that makes the difference between a good and a wear-off part a high irradiation dose was required. Usually, the tribologic interest material is that material being the subject of tribologic processes and represents less than 1% from the mass of the part, being a thin layer of material, distributed over the surface of the bulk part. The usage of accelerators made possible the drastic reduction of the radioactivity level to minimum necessary[3], but to assure the industrial customers on its performances, quality assurance techniques had to be applied [4]. This was called thin layer activation (TLA) method due to short range of stopping charged particles. The protocol with quality assurance has the following stages: 1. Identification of the process and calculation of the required doses of the best-recommended isotope that does not change the material structure. 2. Labeling process planning and accessories design (labeled surface, depth, dose, depth variation) 3. Quality control design (distribution on surface, etc.) Fig.1 – TLA accelerator setup 4. Selecting the part and performing the labeling for radio
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