Materials Science Forum Vol. 985

Abstract: Ceria and zirconia are very important for their thermal, mechanical, and chemical stability, and their thin films have attracted much attention for applications such as buffer layers for growing electric devices, thermal-shield or optical coatings, corrosion-resistant coatings, oxygen sensors and ionic conductors for fuel cells. To investigate and control the thin film orientation and phase is important to improve those performances. In this study, the reciprocal space maps of CeO₂/YSZ/Si(001) were obtained at high temperature by adding a heater to the sample stage. CeO₂ and YSZ thin films were epitaxially grown samples. By measuring lattice constants at high temperature, it was conducted that axes of CeO₂ and YSZ thin films parallel to the substrate surface showed smaller thermal coefficients than bulk reference and axes perpendicular to the surface showed larger thermal coefficients due to the underlayer and Si substrate. The distortion rate of the lattice of each film was small around at the film deposition temperature. And it could be controled the lattice parameter at the film surface by the film thickness. Therefore, when another thin film, for example, SrTiO₃ is deposited on the CeO₂ layer, the lattice change of CeO₂ with increasing temperature may differ from that before depositing the top layer.

Abstract: The main aim of the present paper is evaluated the mechanical properties, microstructures and porosity of Ti6Al4V and CoCrW alloys produced by Laser Powder Bed Fusion (L-PBF) as an additive manufacturing (AM) technology. The mechanical properties were follows: For Ti6Al4V alloy the UTS was 1180 MPa; the YS was in the range <600; 745 MPa>. For CoCrW alloys, the UTS were in range <750; 950 MPa> and YS was in range <400; 500>. Evaluation of porosity was realized on non-etched samples using by quantitative image analysis in order to describe the dimensional and morphological porosity characteristics. The pores in the Ti6Al4V alloy showed homogeneous distribution without significant large pores.

Abstract: Twin-wire indirect arc welding (TWIAW) is a novel welding technology with high deposition efficiency and low dilution rate, which is especially suitable for wear-resistant surfacing. In this study, wear-resistant surfacing layer was prepareted on low-carbon steel using flux cored wire by TWIAW. The influence of welding parameters on droplet transition and the surfacing layers property were studied. In the TWIAW process, due to rapidly solidification of the weld pool, wear-resistant reinforced phase synthesized through metallurgical reaction mainly finished in the droplet transfer stage using the welding arc. The welding parameters not only affected the droplet transfer frequency and size, but also affected the microstructure of the surfacing layer. The main reinforcing phase in the surfacing layer was chromium carbide. "Lean carbon" phenomenon could be observed along the grain boundary in the matrix when the welding current was small. The increasing of the welding current could prompt the metallurgical reaction. The wear resistance of the surfacing layers depends on the distribution of the chromium carbide and the matrix microstructure.