Plasma surface modification of aluminium alloy samples treated with argon discharge conditioning

Abstract

The study of change in surface properties of metals & their alloys under Plasma Processing has a wide range of applications. It affords range, flexibility, ease and accuracy of process control at low cost as compared to other techniques. All the applications of non-equilibrium plasmas involve processes like sputtering, etching, polymerization, surface modification, etc. it is expected for industries to get a final product with specific properties with high reliability and repeata bi I ity .Stainless steel is used to construct UHV chambersComparative study of outgassing rates show that SS can be replaced by Aluminium alloy for UHV chambers Turbomoleculer Pumping Unit evacuates a cylindrical discharge chamber of SS304 with various ports on it. A hollow cathode DC glow discharge in argon for different discharge pressures and for different discharge current densities respectively, is used for treating chemically cleaned ASA6063 Aluminium alloy samples, keeping all other parameters constant. TMP unit evacuates SS304 chamber to a base pressure 3x107 mbar. The processing gas Argon is introduced through a leak valve and with the help of throttling valve the pressure in the discharge chamber is adjusted to the operating pressure10-2mbar. The wall temperature and discharge time were the same in all treatments. The Scanning Electron Microscope (SEM) is used to examine processed surfaces and to study topographical features. The Energy Dispersive Microanalysis by X-rays (EDX) is used to determine the elemental composition of the samples.The results indicate that physical sputtering takes place In Argon GDC, the pits are formed due to etching of the surface by ions, the bombarding ions erode the surface.SEM micrographs show decrease in size of pits with increase in pressure. As pressure increases, molecular densty increases but the number of ionising collisions decreases and their energy may not be enough to etch the surface.The EDX specttum shows peaks corresponding to elements AI, Mg, Ge, Fe & Mn. Absence of any other peak indicates no contamination of the sample surface and no trace of Argon is observed on the sample. Due to nonuniform etching, there is inconsistent increase or decrease in the weight percentage of various elements of Aluminium alloyThe initially confined plasma bunch in vacuum in the absence of magnetic field is unlimitedly expands and cools with time. It occurs that a certain configuration of external magnetic field allows the bunch to accelerate and compress as a whole. Using the exact solution of a system of two 3D Vlasov kinetic equations with a self-consistent electric field and external potential forces [ 1,2], it is possible to predict the dynamics of a two-component plasma bunch in nonstationary weakly inhomogeneous magnetic field in the mirror configuration: B(r,t) = Bo(z,t)e, + B,(x 2 2 + y , z , t ) e , .The dynamics of the plasma in transverse direction is described in adiabatic approximation, which implies the conservation of magnetic momentum of a charged particle. Consequently, the integral d...