Corrosion Behaviour Research Of AZ31Magnesium Alloy And Diamond-Like Carbon Deposited On Its Surface

Magnesium alloy has good mechanical properties, low density, goodbiocompatibility, etc., it was widely used in transportation, aerospace and medicalindustries, and however magnesium alloy was easily corroded, limiting theapplication of magnesium alloy. In recent years, the corrosion resistance ofmagnesium alloys has become a hot research. DLC films with high hardness,corrosion resistance, abrasion wear properties and excellent biocompatibility, was theideal functional materials. In this paper, Plasma Immersion Ion Deposition was usedto deposit diamond-like carbon on the commercial AZ31magnesium alloy surface,this method was presented by the United States Southwest Research Institute. Si-C astransition was aimed to improve the combination of the DLC films and AZ31magnesium alloy. While N and O were added to the DLC films, and thin films ofdifferent thickness were prepared, discussing corrosion resistance of films addeddifferent elements and different thickness in3.5%NaCl solution and Hank’s simulatedbody fluid.DLC film deposited on magnesium alloy section was observed by SEM in thispaper, observing and analyzing thickness and composition, the thickness of C-Si-N、C-Si-O and C-Si-O(thicker)were884nm、460nm and2.21μm，the composition ofdeposited film was accorded with requirement. Scanning the film surface by AFM,three-dimensional image analysis of scanning range, height analysis and roughnesscoefficient analysis were obtained by analysis software, and1#sample was smooth，dense，prefer combination with substrate，low roughness coefficient of surface andgood abrasion resistance.Corrosion rate of AZ31magnesium alloy deposited with C-Si-N、C-Si-O andC-Si-O(thicker)in3.5%NaCl solution and Hank’s simulated body fluid were tested byweightless method and hydrogen collection method; open circuit potential and thepolarization curve of DLC deposited on magnesium alloy and AZ31magnesium alloywere evaluated by electrochemical method, analyzing corrosion behavior of DLCdeposited on magnesium alloy and AZ31magnesium alloy in simulated seawater andsimulated body fluid.Corrosion resistance of magnesium alloy deposited with DLCfilm was increasing,and magnesium alloy deposited with DLC film could be used ashuman implant material.That tensile test of AZ31magnesium alloy, DLC deposited on magnesium alloy,warm rolled magnesium alloy and hot rolled magnesium alloy in air and3.5%NaClsolution was done. In air, the ultimate tensile strength (UTS) of DLC coated magnesium alloy was similar with uncoated magnesium alloy, elongation of theformer was lower than the latter; in3.5%NaCl solution, the maximum fracture stressof DLC coated magnesium alloy was lower than that of uncoated magnesium alloy, itselongation value was higher than uncoated magnesium alloy. In air and3.5%NaClsolution, UTS of hot rolled magnesium alloy was lower than warm rolled magnesiumalloy, elongation of the former was higher than the latter.