Magnesium alloys are next generation biodegradable implants for clinical applications. However, their medical applications are currently hampered by their rapid corrosion rate in the physiological environment. To overcome such limitations, we have applied a novel layer-by-layer engineering approach of introducing anodization-induced microrough oxidized surface on ZK60 magnesium alloy, followed by surface mineralization with natural calcium apatite (hydroxyapatite, HA), and surface coating with natural protein (silk fibroin, SF); which, effectively reduces corrosion and degradation rate of ZK60 in simulated body fluid. Anodization of ZK60 improved the surface adhesion strength of HA layer; HA layer increased the surface roughness, hydrophilicity and micro-hardness, whereas decreased ionic release; SF layer decreased surface microroughness and hydrophilicity, whereas improved the stability of HA layer. The SF + HA coating on anodized ZK60 effectively decreased the in vitro weight loss (degradation) by almost six times, whereas corrosion rate by more than two orders in magnitude. Such interfacial coatings, with biocompatible SF on the outer surface, could potentially expand the application of ZK60 in the field of biomedical engineering.
A hot filament thermal chemical vapor deposition (CVD) reactor was used to deposit solid thin films on stainless steel 316 (SS 316) and stainless steel 201 (SS 201) substrates at different flow rates of acetylene (C2H2) gas. The variation of thin film deposition rate with the variation of gas flow rate has been investigated experimentally. During experiments are conducted under gas flow rate (1-5) lit/min gas flow rate, duration of deposition (10-60 min), pressure (0.2-1 bar), average surface roughness (0.3-1.05) µm and temperature 800 °C considered. Experimental results show that deposition rate on SS 316 and SS 201 increases with the increase in gas flow rate. The deposition rate also shows increasing trend with pressure and duration of deposition. Under the above mentioned experimental conditions deposition is found to be maximum of SS-316 compared to SS-201. In relation to roughness the maximum deposition is found at 0.5 microns but comparing the both materials -316 and-201 highest of deposition rate is obtained from SS-316.
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