Most recent issue published online for the International Journal of Materials and Product Technology.

Pressureless sintering of silicon nitride ceramics with porous gradient structure for gas filter application

Fei Chen; Lingling Ma; Qiang Shen; Chuanbin Wang; Lianmeng Zhang — 2012-01-15T23:20:50-05:00

Pressureless sintering of silicon nitride ceramics with porous gradient structure for gas filter application
Fei Chen; Lingling Ma; Qiang Shen; Chuanbin Wang; Lianmeng Zhang
International Journal of Materials and Product Technology, Vol. 42, No. 1/2 (2011) pp. 3 - 11
In the present study, Si3N4 ceramics with high porosity and porous gradient structure are prepared by pressureless sintering technique. Si3N4 ceramics with porosity of 34-47% are prepared by using ZrP2O7 as a binder material and heat treated at 1000°C in a nitrogen atmosphere. Si3N4 ceramics with porosity of 50-70% are prepared by using ZrP2O7 as a binder material, starch or naphthalene as a pore-forming agent and then heat treated at 1000°C in a nitrogen atmosphere. Si3N4 ceramics with porous gradient structure are then formed by laminating the Si3N4 porous ceramics with ordered porosity, followed by sintering at 1000°C. The phase compositions are analysed by X-ray diffraction (XRD), and the microstructure of the sintered samples is observed by scanning electronic microscope (SEM). The results show that the obtained Si3N4 ceramics exhibit a good porous-graded structure from high porosity to low porosity. The major phase of Si3N4 ceramics is still α phase.

Fabrication of Si3N4-based seal coating on porous Si3N4 ceramics

Qiang Shen; Ying Yang; Fei Chen; Lianmeng Zhang — 2012-01-15T23:20:50-05:00

Fabrication of Si3N4-based seal coating on porous Si3N4 ceramics
Qiang Shen; Ying Yang; Fei Chen; Lianmeng Zhang
International Journal of Materials and Product Technology, Vol. 42, No. 1/2 (2011) pp. 12 - 20
In this study, Si3N4-based seal coatings using MgO, Al2O3 and SiO2 as the sintering additives were prepared on the porous Si3N4 substrates by room temperature spraying and pressureless sintering. The composition of the Si3N4-based seal coatings was well designed, in order to both match the coefficient of thermal expansion with that of the porous Si3N4 substrate and form the liquid phase at a relative low temperature. During the sintering process, the liquid phases promote the densification and homogenisation of the Si3N4-based seal coatings. A good combination between Si3N4-based seal coatings and substrate is achieved, as a result of the liquid-phase penetration into the pores in the porous Si3N4 substrate.

Design and joining of graphite to copper by a simple direct casting technology

Zhangjian Zhou; Zhihong Zhong; Dandan Qu; Changchun Ge — 2012-01-15T23:20:50-05:00

Design and joining of graphite to copper by a simple direct casting technology
Zhangjian Zhou; Zhihong Zhong; Dandan Qu; Changchun Ge
International Journal of Materials and Product Technology, Vol. 42, No. 1/2 (2011) pp. 21 - 28
A simple low-cost direct casting technology has been developed for joining graphite and copper. The direct casting of copper on graphite was possible through mixing transition metal (Cr) powders with Cu powders to decrease the contact angle between graphite and copper and form a carbide layer at high temperature (>1100°C) in a vacuum furnace for 20-80 min. For decreasing the coefficient of thermal expansion of copper alloy, refractory metal W powders were also added into the mixed powders. The reaction between the transition metal and graphite determined the formation of a thin carbide layer on the graphite surface, as detected by X-ray diffraction analysis. The cross-section of the joined samples was observed by SEM. The shear strength of the C-Cu joints was measured at room temperature with a compression machine.

Fabrication of functionally graded grinding wheel by a centrifugal mixed-powder method for CFRP-drilling applications

2012-01-15T23:20:50-05:00

Fabrication of functionally graded grinding wheel by a centrifugal mixed-powder method for CFRP-drilling applications
Yoshimi Watanabe; Eri Miura-Fujiwara; Hisashi Sato; Kunio Takekoshi; Hideaki Tsuge; Tadashi Kaga; Naoyuki Bando; Shigemasa Yamagami; Kazumasa Kurachi; Hisanori Yokoyama
International Journal of Materials and Product Technology, Vol. 42, No. 1/2 (2011) pp. 29 - 45
We are developing functionally graded grinding wheels fabricated by a centrifugal mixed-powder method. As a first step of this fabrication method, a powder mixture of abrasive particles and metal matrix particles is inserted into a spinning mould. After that, a metal matrix ingot is melted and then the molten metal matrix is poured into the spinning mould with the powder mixture. As a result, the molten metal matrix penetrates into the space between the particles due to the pressure exerted by the centrifugal force. At the same time, the metal matrix powder is melted by the heat from molten matrix poured from the crucible. Finally, a ring-shaped sample with abrasive particles distributed on its surface (functionally graded grinding wheel) can be obtained. In this study, functionally graded grinding wheel fabricated by the centrifugal mixed-powder method will be reported.

Study of strength and toughness in Japanese sword produced from Tamahagane steel by Tatara process

2012-01-15T23:20:50-05:00

Study of strength and toughness in Japanese sword produced from Tamahagane steel by Tatara process
M. Yaso; T. Takaiwa; Y. Minagi; T. Kanaizumi; K. Kubota; Y. Noda; Ananda Kumar Das; S. Morito; T. Ohba
International Journal of Materials and Product Technology, Vol. 42, No. 1/2 (2011) pp. 46 - 55
Several metallurgical properties of a traditional Japanese sword were investigated from sharp edge to core area in cross-section and on surface. The microstructure is found to be lath martensite at the sharp edge and the prior austenite grain size is observed to be very fine. Towards the inside from the sharp edge in the cross-section, the microstructure changes gradually from hard martensite to soft ferrite. Micro hardness along the centre line in the cross-section was measured. The sharp edge is very hard and the hardness decreases drastically with the detachment from the sharp edge. The hardness gradient on the hardness distribution curve, tan θ is defined here. The value of tan θ is estimated as an important factor for the explanation of mechanical properties of Japanese swords. Furthermore, residual stress was measured with XRD. Large compressive stress is consequently found on the surface including the sharp edge, which is effective for strengthening the Japanese sword.

Impact performance of Al/SiC functionally graded circular plates

M. Kemal Apalak; Recep Gunes; Murat Aydin; J.N. Reddy — 2012-01-15T23:20:50-05:00

Impact performance of Al/SiC functionally graded circular plates
M. Kemal Apalak; Recep Gunes; Murat Aydin; J.N. Reddy
International Journal of Materials and Product Technology, Vol. 42, No. 1/2 (2011) pp. 56 - 65
This experimental study addresses the effect of ceramic reinforcement on the impact performance of functionally graded (FG) circular plates. The FG circular plates were produced from two different ceramic (SiC or Al2O3) and metal (Al) combinations using powder stacking-hot pressing technique. The Al/SiC FG circular plates exhibited better impact resistance than Al/Al2O3 FG circular plates. The effect of ceramic particle size was also investigated on the impact performance of specimens with different composition variations. A ceramic particle size of 50 μm improved the impact performance. In addition, the material composition and impactor velocity also affected the impact performance. Thus, the contact force increases as the composition changes from metal-rich to ceramic-rich. The peak contact force increases with increasing the velocity of impactor.

Thermoelectric properties and conduction mechanism of conductive polythiophenes

2012-01-15T23:20:50-05:00

Thermoelectric properties and conduction mechanism of conductive polythiophenes
Yoshikazu Shinohara; Yukihiro Isoda; Kentaro Hiraishi; Akito Masuhara; Hidetoshi Oikawa
International Journal of Materials and Product Technology, Vol. 42, No. 1/2 (2011) pp. 66 - 73
In this study, we synthesised conductive polymers of polythiophene series and evaluated their thermoelectric properties in the temperature range from 88 K to 350 K. Poly-hexylthiophenes showed a conduction mechanism of the nearest-neighbour distance hopping (NDH) in the measured temperature range, while the main conduction mechanism of polythiophenes was the variable range hopping (VRH). Only polythiophenes with low electrical conductivity (such as 0.02 S/cm) presented NDH at temperatures of below 200 K. The conduction mechanism is changed by the distance between the thiophene main chains and the kinetic energy of carriers.

Molecular dynamics study on the mechanical characteristics of Al-terminated Al/α-Al2O3 interface under tensile loading

Xin Lai; Lisheng Liu; Hai Mei; Pengcheng Zhai — 2012-01-15T23:20:50-05:00

Molecular dynamics study on the mechanical characteristics of Al-terminated Al/α-Al2O3 interface under tensile loading
Xin Lai; Lisheng Liu; Hai Mei; Pengcheng Zhai
International Journal of Materials and Product Technology, Vol. 42, No. 1/2 (2011) pp. 74 - 86
Molecular dynamics simulation has been performed to study the mechanical properties and behaviour of the interface between Al and Al-terminated α-Al2O3 under tension loading. The atomistic structures of the metal/ceramic interface are first modelled according to experimental results. The interatomic potential utilised here is a multicomponent potential proposed by us. The results reveal that atomic rearrangement caused by lattice misfit occurs after relaxation, expressed as the stacking-fault islands at the interface, which shows reasonable agreement with experiments. During the tension process, the system reaches its ultimate strength 7.89 GPa at strain 11.08% when the crack nucleation emerges in the aluminium.

Numerical simulation on the impact resistance of functionally graded materials

Jiangtao Zhang; Mei Zhang; Pengcheng Zhai; Lisheng Liu; Huiji Shi — 2012-01-15T23:20:50-05:00

Numerical simulation on the impact resistance of functionally graded materials
Jiangtao Zhang; Mei Zhang; Pengcheng Zhai; Lisheng Liu; Huiji Shi
International Journal of Materials and Product Technology, Vol. 42, No. 1/2 (2011) pp. 87 - 97
The stress wave propagation and damage evolution within the sandwich structure of ceramic faceplate/Functionally Graded Materials (FGMs) interlayer/metal backplate are numerically studied in this paper. The microstructure models of FGM interlayer are constructed by introducing a new algorithm based on Voronoi discretisation. Four typical microstructure models of FGM interlayer with different composition gradient are constructed to analyse the effect of composition gradient of FGM interlayer on the stress wave propagation and damage evolution in the sandwich structures under impulse loading. The results demonstrate that the composition gradients of FGM interlayer significantly affect the stress propagation and damage evolution in the sandwich structures. The unidirectivity of stress wave in these models varies with the variation of composition gradient, and a slow variation of composition gradient is helpful for reducing the stress on the surface of backplate.

Numerical simulation on the interface debonding in solid propellant under large deformation by a cohesive zone model

Mei Zhang; Jiangtao Zhang; Pengcheng Zhai; Lisheng Liu; Huiji Shi — 2012-01-15T23:20:50-05:00

Numerical simulation on the interface debonding in solid propellant under large deformation by a cohesive zone model
Mei Zhang; Jiangtao Zhang; Pengcheng Zhai; Lisheng Liu; Huiji Shi
International Journal of Materials and Product Technology, Vol. 42, No. 1/2 (2011) pp. 98 - 109
A new algorithm based on the artificial interaction force between neighbouring particles are introduced to build microstructure models of solid propellant, and the numerical simulation on the non-linear properties of solid propellants under large deformation are performed by using the remeshing technique based on the finite element code ANSYS. The binder/particle interface debonding is modelled through cohesive zone models. The results show that the interface debonding of large particles precedes that of small particles. The overall strains at which interface debonding takes place and the predicted effective stresses of propellants decrease with the decreasing of interface strength. At large strains, the load is mainly carried by the binder network, which is formed due to severe interface debonding. The simulated microscopic deformation modes of solid propellants are well consistent with those of experiments.

Experimental study on cross-section distortion of thin-walled rectangular 3A21 aluminium alloy tube by rotary draw bending

Kuanxin Liu; Yuli Liu; He Yang; Gangyao Zhao — 2012-01-15T23:20:50-05:00

Experimental study on cross-section distortion of thin-walled rectangular 3A21 aluminium alloy tube by rotary draw bending
Kuanxin Liu; Yuli Liu; He Yang; Gangyao Zhao
International Journal of Materials and Product Technology, Vol. 42, No. 1/2 (2011) pp. 110 - 120
The cross-section distortion is inevitably produced in rotary draw bending process of thin-walled rectangular 3A21 aluminium alloy tube, which severely affects the forming quality of the tube. To predict and control cross-section distortion, the experiments with different process parameters are carried out. It is indicated that the effects of bending angle, core number and clearance between the pressure die and tube on the cross-section distortion are significant, but the effects of clearance between wiper die and tube and the boost velocity of the pressure die can be neglected. The maximum cross-section distortion is produced in the section of the angle 50°, and the position does not change with the variation of the process parameters. The results are of significance in the determination of the process parameters for the rotary draw bending process of rectangular tube.

Low-voltage silicon chip/glass ring anodic bonding for MEMS device packaging and experimental evaluation of bonding quality

Quan Wang; Ran Hu; Xiaodan Yang; Jianning Ding — 2012-01-15T23:20:50-05:00

Low-voltage silicon chip/glass ring anodic bonding for MEMS device packaging and experimental evaluation of bonding quality
Quan Wang; Ran Hu; Xiaodan Yang; Jianning Ding
International Journal of Materials and Product Technology, Vol. 42, No. 1/2 (2011) pp. 121 - 129
Packaging technologies are a great issue in MEMS/NEMS device fabrication. Silicon to glass anodic bonding is a common bonding technique for packaging. In this paper, we describe low voltage silicon chip/glass ring anodic bonding to meet the need of MEMS device batch fabrication. The bonding voltage decreases to be 160 V and the bonding time is cut down from 30 minutes to be about two minutes. The anodic bonding quality of silicon chip/glass ring, effects of thermal cycling and thermal shock, are evaluated in details. The bonding strength is measured using a tensile tester and the fracture mainly occurs inside the silicon chip rather than along the interface. The bonding surface has large adherence intension and can work under harsh environment.