The porous scaffolds of silk fibroin-chitosan /nano-hydroxyapatite (SF-CS / n-HA) were fabricated through the freeze- drying technique. Component, structure and morphology of scaffolds were studied by infrared (IR), X-ray diffusion (XRD) and scanning electron microscope (SEM), and the mechanical properties of the scaffolds were measured. The simulated body fluid (SBF) experiments were conducted to assess the bioactivity of the scaffolds. Results indicate that chemical binding is formed between HA and organics, the macropore diameter of the scaffolds varies from 150 to 400μm. The porous scaffolds with interconnected pores possess a high porosity of 78%-91% and compressive strength of 0.26 -1.96MPa, which can be controlled by adjusting the concentration of organic phases and prefreezing temperature. In the SBF tests, a layer of randomly oriented bone-like apatite crystals formed on the scaffold surface, which suggested that the composite material had good bioactivity. Studies suggest the feasibility of using SF-CS /n-HA composite scaffolds for bone tissue engineering.

Silk fibers were introduced into hydroxyapatite(HA)/chitosan(CS) matrix to prepare scaffold materials of bone tissue engineering with the adequate initial strength and improved cellular affinity using combination of in situ synthesis and freeze-drying technique. Chemical component was investigated using X rays diffraction (XRD) and Fourier transform infrared spectrum (FTIR). Structure and morphology of the composites were observed by scanning electron microscope (SEM). Porosity was tested by liquid substitution method. The mechanical properties of the composites were also measured. The simulated body fluid (SBF) and the cell culture experiments were conducted to assess biological properties of the composites. Results show that the composites with a pore size of 100~250μm have a porosity of 75%~90%and the maximum compressive strength of 5.7 MPa. The compressive strength of the composite is greatly improved in comparison with that of HA/CS matrix (4.6 MPa). In the SBF tests, a layer of randomly oriented apatite crystals form on the scaffold surface after sample immersion in SBF. The cell culture experiments show that the osteoblast cells are attached and proliferated on the surface of the composite, which suggests good bioactivity and cellular compatibility of the composite material. It is concluded that the composites have a promising prospect as bone tissue engineering materials.

According to Cr-Ni stainless steel, three different welding technology and the appropriate welding process parameters were selected. Three welded joints of Cr-Ni stainless steel were prepared. The microstructure in weld metal zone of Cr-Ni stainless steel under different welding methods was studied by X-fluorescent chemical composition analysis and microstructure analysis. The results show that alloy composition of the weld metal are different and distribute unequally under different welding methods, microstructure morphology and grain size of the weld layer are quite different. the structure of bottom is small amount of γ phase and a little δ phase are combined together and cover is γ phase and Cu-wealthy phases in the welds under TIG-MAG welding. the structure of bottom is coarse columnar crystal and cover is typical cellular dendrite in the welds under TIG- TIG welding. the structure of bottom is tiny equiaxial dendrites and columnar crystal and cover is some γ phase and a little δ phase are combined together in the welds under TIG-SMAW welding.

Calcium phosphate biocoatings were fabricated on the surface of magnesium alloy by micro-arc oxidation (MAO) technique. The properties of biocoatings related with MAO technics parameters and the electrolyte constitute. The surface morphology, constitute and friction coefficient were studied by SEM XRD and fret test machine. The results indicated that the optimum electrolyte was CaCO3-Na3PO4 contained 20g/L phosphate ions and 1.5 Ca/P ratio, and the optimum technics parameters was 350V oxidation voltage for10min, 500HZ pulse frequency and 1:10 in duty cycle. The main phase constitutes of the porous biocoatings contained were Mg, MgO, Mg3(PO4)2 and CaNaPO4. The anode polarization potential of the coating was -1.36V and enhanced about 0.29V compared with that of magnesium alloy substrate, which indicated that the biocoatings had better corrosion resistant properties. The friction coefficient of the biocoatings was 0.23 and decreased 0.15 compared with that of magnesium alloy substrate, which indicated that the biocoatings had better wear resistant properties. The biocoatings could induce hydroxyapatite to form on its surface after soaked in body fluid, which showed that the composite coatings owned good bioactivity.

Porous hydroxyapatite bioceramics were obtained by impregnating the polyurethane sponge with rheologically optimized slurry. 6wt% bioglass was doped into hydroxyapatite to act as a sintering additive. Thermal analysis was used to study the pyrolysis process of the polyurethane sponge. Phase component and surface morphology were characterized by X-ray diffraction and scanning electron microscopy, respectively. It was found that hydroxyapatite was the main phase composition of the porous ceramics sintered at 1250°C. The porous bodies prepared had an open, uniform and interconnected structure with pore size of 200-400μm. The porous ceramics possessed high porosity of 70-80% and compressive strength of 2.3MPa. The precipitates formed on the surface of the porous ceramics might be bone-like apatite after immersion in a simulated body fluid for various periods.