Papers by Author: Wen Bo Han

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Authors: Zhu Ju Wang, Wen Bo Han, Shu Qing Tao, Ying Wu
Abstract: Over the last 100 years innovative techniques in the fabrication of ceramics have led to their use as high-tech materials. Inert bioceramics, such as ZrO2, have inherently low level of reactivity compared with other materials such as polymers and metals as well as surface reactive or resorbable ceramics. The aim of this study was to validate the effect of incision using a zirconia inert bioceramic scalpel to incise animal body and to prove incision property of tissues before clinic. The experiments of incisions concrescence using a sterilized Zirconia inert bioceramic scalpel were investigated in this paper. We used 4-month-old inbred line SD rats as experiment animals. They were divided into three groups to undergo incision on the back skin and subcutaneous tissue. The subcutaneous tissue and musculature samples were obtained and analyzed by optical microscopy at 3, 7 and 14 days for histopathological evaluation respectively. The experimental results showed that no wound dehiscence was observed after suture removal at 14 days after the operation. The experiments proved that an inert bioceramic scapel was nontoxic, nonallergenic, and noncarcinogenic for incisions that obtained normal concrescence criteria two weeks after operation.
2115
Authors: Ning Li, Ping Hu, Xing Hong Zhang, Wen Bo Han
Abstract: This paper presented the application of microwave-discharge plasma apparatus which was used to evaluate the catalytic properties of ZrB2-based ultra-high temperature ceramics in the simulated real service environment by the wall temperature response method based on the heat balance principle. The results showed that the material composition had a significant influence on the catalytic properties of ZrB2-based ultra-high temperature ceramics, and the catalytic activity of ZrB2-SiC composites with Cr addition had been increased significantly. The relationship between catalytic properties of ZrB2-based ultra-high temperature ceramics and surface composition was discussed in detail. The composition optimization was considered to be a very effective way to inhibit the recombination reactions of dissociated atoms on the surface of ultra-high temperature ceramics.
636
Authors: Guo Qing Chen, Shao Hua Sui, X.D. Wang, Wen Bo Han
Abstract: In this paper constrained extrusion of the zirconia dispersed alumina nanocomposite under superplastic conditions was conducted. The mechanical properties of deformed material were studied and its results were compared with those of the initial materials. The microstructure evolution during superplastic deformation was also analyzed. The results demonstrated that after superplastic extrusion the flexural strength, relative density, Vickers hardness as well as fracture toughness of the material increased noticeably. The flexural strength of the deformed composite even retained at a high value of 310MPa at 800°C. The fracture toughness of the material increased from 6.92 MPa·m1/2 to 8.87 MPa·m1/2 after deformation. After superplastic extrusion due to grain boundary sliding and the compressive stress state, the internal porosities in as-sintered materials were eliminated. During extrusion with grain coarsening the effect of t-ZrO2 to m-ZrO2 transformation toughening increased because more zirconia grains reached the critical dimension. Although grain coarsening may cause the decrease of the fracture toughness in some extent, the phase transformation toughening and strengthening dominated. As a result, the mechanical properties of the deformed material were improved.
527
Authors: Xin Sun, Xing Hong Zhang, Zhi Wang, Wen Bo Han, Chang Qing Hong
Abstract: Abstract. ZrB2-SiC ultra-high temperature ceramics (UHTCs) was hot-pressed at a temperature of 1900°C with the addition of carbon black as a reinforcing phase. Microstructure and mechanical properties were investigated. Analysis revealed that the amount of carbon black had a significant influence on the sinterability and mechanical properties of ZrB2-SiC ceramics. When a small amount ( < 10 vol.%) of carbon black was introduced, it may react with oxide impurities (i.e. ZrO2, B2O3 and SiO2) present on the surface of the starting powder, thus promote the densification and grain refining of ZrB2-SiC ceramics. As a result, the mechanical properties including flexural strength and fracture toughness were improved. However, with the further adoption of carbon black, mechanical properties were not improved much, which could be attributed to the redundant phase at grain boundaries. The results presented here point to a potential method for improving densification, microstructure and mechanical properties of ZrB2-based ceramic composites.
185
Authors: Wen Bo Han, Zhu Ju Wang
Abstract: Hydroxyapatite is a kind of ideal biomaterials for bone and teeth replacement, but its low strength and brittleness need to improve. As bone replacing materials, hydroxyapatite (HAP) and zirconia both have advantage and disadvantage. Nano-sized HAP-ZrO2 powders and HAP-TZP (3Y) (3mol% yttria - stabilized cubic zirconia) bioceramic for artificial joint have been fabricated in this paper. The nano-sized HAP-ZrO2 powders with homogeneous distribution could be synthesized by two-step precipitation method. The HAP-TZP bioceramic with small grain size could be obtained by using hot-press sintering technology, and the sintering parameters are: sintering temperatures T=1300°C, sintering pressure p=30MPa and sintering time t=30min. The mechanical properties, microstructures and fracture pattern that were analyzed by SEM and optical microscopy of the HAP-TZP bioceramic were investigated systematically. The results show that no reaction between HAP and ZrO2 powders, which could be attributed to the very short sintering time of hot press sintering.
2119
Authors: Xi Feng Li, Kai Feng Zhang, Wen Bo Han, Guo Feng Wang
Abstract: The deformation behavior of gas pressure forming of amorphous Fe78Si9B13 alloy was investigated under equibiaxial tension. The gas pressure forming was carried out in the temperature range of 430°C~530°C below the crystallization temperature Tx and die apertures of 5mm~10mm. The dome height and amorphous ribbon thickness of deformed specimens at the pole was measured. It was found that amorphous Fe78Si9B13 alloy had exhibited good plasticity in the experimental temperature range. The near-semisphere specimens of the radius 5mm and the height 4.5mm were obtained from the gas-pressure forming at 450°C and 530°C for 30min, which is similar to the superplastic forming.
575
Authors: Hongying Dong, Wen Bo Han, Shu Jie Li
Abstract: The investigation on joining of SiC to SiC has been conducted for some years. It is essential that the mechanical and thermal properties of the joints should meet the requirements of engineering. In view of the fact that the ternary carbide Ti3SiC2 has shown unique mechanical and thermal properties, it is promising to join SiC to SiC using ternary carbide Ti3SiC2 as filler (welding compound), and this is the subject to deal with in this paper. The joining of SiC to SiC has been successfully realized by hot pressing reaction joining process using Ti3SiC2 powder as filler. The optimized technological parameters have been obtained by orthogonal experiments, under which the achieved weld strength is higher than that of the welding base material SiC ceramic. Ti3SiC2 is stable up to 1200oC in Ar atmosphere with an external pressure. At the joining temperatures of 1300~ 1600oC the main phases of the interface are Ti3SiC2, TiC and TiSi2. The mechanism of bonding at the interface is interdiffusion and chemical reaction.
1255
Authors: Wen Bo Han, Peng Wang, Yang Hou
Abstract: ZrB2-based ceramic composites were prepared through hot-pressing at a temperature of 1880°C. An intragranular microstructure was achieved because of the existence of nanoSiC. In this paper, the mechanical properties of ceramic materials of ZrB2-SiC-G were studied, and the influence of intragranular microstructure on the mechanical properties was analyzed. The values of flexural strength and fracture toughness of ZrB2-20vol%SiCnp-15vol%G reached 551.9MPa and 5.25MPa·m1/2, respectively. Compared to ZrB2-20vol%SiC-15vol%G with micro-SiC, the fracture toughness was improved.
560
Authors: Bao Xia Ma, Wen Bo Han, Xing Hong Zhang
Abstract: Ternary ZrC-SiC-ZrB2 ceramic composites were prepared by hot pressing at 1900 °C for 60 min under a pressure of 30 MPa in argon. The influence of ZrB2 content on the microstructure and mechanical properties of ZrC-SiC-ZrB2 composites was investigated. Examination of SEM showed that the microstructure of the composites consisted of the equiaxed ZrB2, ZrC and SiC grains, and there was a slight tendency of reduction for grain size in ZrC with increasing ZrB2 content. The hardness increased considerably from 23.3 GPa for the ZS material to 26.4 GPa for the ZS20B material. Flexural strength was a strong function of ZrB2 content, increasing from 407 MPa without ZrB2 addition to 627 MPa when the ZrB2 content was 20vol.%. However, the addition of ZrB2 has little influence on the fracture toughness, ranging between 5.5 and 5.7 MPam1/2.
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