Nickel(II) Oxalate Dihydrate / Thermal Decomposition / Temperature Programmed-XRD / TGA-FTIRThe non-isothermal decomposition of NiC 2 O 4 · 2H 2 O was investigated under a dynamic inert atmosphere using a temperature-programmed X-ray diffractometer (TP-XRD) and a thermogravimetric analyzer coupled to a Fourier-transform infrared spectrometer (TGA-FTIR). Both solid and gaseous products were analyzed in situ. The XRD pattern of the dehydration product did not match data for NiC 2 O 4 reported in the JCPDS file. The thermal decomposition of the dehydration product (NiC 2 O 4 ) took place in two sub-steps, both of which involved CO 2 evolution. Metallic nickel was the final product.

The parameters to prepare α-Al 2 O 3 coatings by double glow plasma technique were optimized to obtain dense and thick α-Al 2 O 3 coatings on 316 L stainless steel at low temperature of 580 °C. The parallel distance between the source electrode and the substrate, working pressure, source electrode voltage, and workpiece electrode voltage were designed by L9 Orthogonal array design. The thickness, microstructure, chemical composition and phase components of the sputter-deposited Al/α-Al 2 O 3 coatings were analysed by means of 3-D non-contact surface profiler analysis, scanning electron microscopy equipped with energy dispersive X-ray spectrometry and glancing-angle X-ray diffraction, respectively. The results indicated that the parallel distance between the source electrode and the substrate played a dominant role in determining the thickness of the films. The coatings prepared at the optimum parameters exhibited a very dense, uniform, and compact microstructure without any cracks and defects. It was found that iron aluminide formed at the interface between the coatings and the substrates. The thickness of the coatings reached about 11.6 μm at the deposition rate of ~64.4 nm min -1. The oxidized coatings with the lowest porosity about 0.13 % had relative content of α-Al 2 O 3 as high as 66.5 % when oxygen flow was 2 sccm.