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Diffusion bonding of Ti-6Al-4V (TC4) to oxygen free copper (OFC) at low temperature was carried out using silver foil as interlayer. Results show that the interlay can prevent the formation of brittle Ti-Cu compounds and improve the interfacial microstructure and bonding strength of the TC4/OFC joint. Moreover, adding the silver interlayer greatly lowers the bonding temperature. The composition of the joint from the TC4 side to the OFC side is TC4 substrate, AgTi compound, Ag interlayer, Ag-Cu solid solution and OFC substrate. The tensile strength of the joint bonded at 700 °C for 1 h under 10 MPa bonding pressure has an excellent value of 150 MPa, higher than those previously reported in literatures. Fracture failure takes place in the Ag/OFC interface and ductile fracture can be observed on the fracture surface. It is suggested that the ductile properties of the AgTi compounds are superior to that of Ag-Cu solid solution in this joint.

A newly developed rapid densify technique, spark plasma sintering (SPS), is used to prepare full-densified aluminum nitride (AlN) ceramics which are poorly sinterable. Some sintering aids are also used to promote the AlN ceramics' densification and improve its thermal conductivity. In this work, effects of sintering aid Li2O on densifica- tion, microstructure and thermal property of SPS sintered AlN ceramics were investigated. Results suggest that the ini- tial sintering temperature of AlN samples reduce from 1550℃ to lower than 1200℃ with 1.0wt% Li2O and 1.5wt% Sm2O3 (or Y2O3) adding as sintering aids . With Li2O addition, AlN compacts can be fully densified at 1650℃. The microstructure of AlN compacts indicates that Li2O is beneficial to generate aluminate liquid phase with better wet- tability and promote the densification of AlN ceramics, but it is unable to obtain higher relative density of AlN com- pacts because the escapement of gas phase though out liquid phase is very difficult in a rapid sintering process. Meanwhile, Li2O addition affects the growth of AlN grains, and the better wettability of aluminate with AlN grain in- duces the homogeneous distribution of grain boundary phase. The deterioration of thermal conductivity of AlN ceram- ics is caused by the fact that the scattering of phonon is enhanced by small grain size and the secondary phase spreading adequately along the AlN grain boundaries. The thermal conductivity of AlN samples with 1.0wt% Li2O and 1.5wt%Sm2O3 as sintering aids is lower than that of sample only with Sm2O3 as sintering aids.

It is very difficult to prepare full-densified aluminum nitride-boron nitride (AlN/BN) composite ceramics with homogeneous microstructure and high thermal conductivity. Spark plasma sintering (SPS) was used to fully densify the AlN/BN composites in this work. Microstructure, mechanical properties and thermal conductivity of the SPS sintered AlN/BN composites with 5–30 vol% BN were investigated. The results show that the microstructure of composites is fine and homogenous, and the AlN/BN composites exhibit high mechanical properties. To promote the growth of AlN grains and modify the distribution of grain boundary in AlN/BN composites, a heat treating methodology was introduced through gas pressure sintering (GPS). This processing was significantly beneficial to enhancing the thermal conductivity of the specimen. The thermal conductivity of AlN/BN composites with 5–30 vol% BN reached 60 W/m·K after the samples were treated by GPS.

Needle-like hydroxyapatite crystals were synthesized by homogeneous precipitation method with water-soluble calcium salts and phosphates. The work focuses on the analysis of influencing factors on length and lengh/diameter ratio of hydroxyapatite crystals, which are main characteristics of reinforcement materials. The effects caused by system temperature, concentration of nutrient, and additives are discussed, and the optimum reacting condition is given.

A new kind of in-situ ceramic consolidation molding process was investigated on the basis of the characteristics of starch swelling in water and gelatinizing when heated. The SiC ceramic suspension containing about 50vol% solids loading and about 3wt% starch can be cast and molded into various complex-shape SiC ceramic parts in a water-thermostat. The dry shrinkage of the green body was less than 1.0% when the solid volume fraction of SiC suspension was up to 52.5%. The density and pore size were homogeneously distributed inside the biscuits. Soaked with melt silicon in a vacuum arc furnace, the biscuits were turn into SiC ceramic materials with homogeneous structure and high performances.

This paper discussed the preparing process of hydroxyapatite fibers which were widely used as reinformcement for biomedical materials by homogeneous precipitation method. The needle-like hydroxyapatite crystals were synthesized in an aqueous system. They were transferred from precursors-dicalcium phosphate anhydrate and octacalcium phosphate crystals. The reaction conditions were well controlled in order to obtain crystals in given morphology. The products were characterized by X-ray powder diffractometry (XRD), scanning electron microscopy (SEM) and infrared spectroscopy(IR). They were verified to be hydroxyapatite crystals with needle-like in shape.