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Key engineering materials
Trans Tech Publications Ltd.
Key engineering materials

Trans Tech Publications Ltd.

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1013-9826

Key engineering materials/Journal Key engineering materials
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    An Experimental Study on Brazing of Diamonds onto Thin Steel Wires

    Guoqing ZhangHui HuangXipeng Xu
    P.537-542页
    查看更多>>摘要：An experimental investigation was carried out to braze diamond abrasives onto thin steel wires, in which case the brazing was conducted in the vacuum and under high temperatures by using a nickel-based powder as brazing alloy. The morphologies and microstructures of the brazed wires were observed and the comprehensive mechanical properties of the brazed wires were tested. The brazed wires were also used to cut such brittle materials as ceramics, glass, and natural stone. It is shown that a typical phenomenon of brazing alloy's climbing around the diamond grains was observed in brazing the wires. Through observing the cross-section of brazed wires, it is observed that there is a good bonding between the brazing alloy and the body of steel wires. The crystal grains of the steel wires grew significantly after brazing. Through observing the morphologies of the diamond wires and the surfaces of four workpiece materials, few diamond pull-outs were found on the wires and the kerfs on the workpiece materials were basically flat.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Optimal Parameter Design of Solder Residue in Flip Chip Process by Using Taguchi Method

    Jian-Long KuoKai-Lun ChaoChun-Cheng Kuo
    P.543-548页
    查看更多>>摘要：Because the solder residue was found in the manufacturing process which greatly affected the product quality, the purpose of this paper was to make the product quality improved and to find an optimal solution for process parameters in the flip chip process. The experimental testing was based on SMT manufacturing process. The amount and size of solder left on passive component in the process of manufacturing were considered as the quality traits. Since too many solders left on the passive component side during flux cleaning process, it was possible that the balling would be flowed into the chip, which caused the bump short in the chip and affected the quality of the product. In this paper, orthogonal array by using Taguchi method is adopted as the effective experimental method with the least experimental runs. Also, based on the quality evaluation of signal-to-noise ratio, the ANOVA is used to evaluate the effects of quality target according to the experimental results. The results reveal that the optimization in the process is confirmed. Therefore, this study can effectively improve the solder residue in semiconductor manufacturing process.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    A New Solution Method for Homogenization of Effective Properties of Electromagnetic Honeycombs

    Lianhua MaBernard F. RolfeQingsheng YangChunhui Yang...
    P.551-556页
    查看更多>>摘要：In this paper, an analytical model and its new numerical solution using the homogenization method are developed to determine the effective electromagnetic characteristics of honeycombs. Based on the proposed solution method, the electromagnetic properties are obtained by employing the multi-scale homogenization theory and periodical electric (magnetic) potential boundary conditions. Further, the effect of geometry of honeycomb's unit cell on effective electromagnetic properties is investigated with the use of the proposed method. The numerical results are compared with analytic results using the Smith-Scarpa's semi-empirical formula.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Surface Roughness and Stress Responses of a Feldspar Porcelain to Fatigue Impact

    Richard LymerLing YinZhongxiao PengRobert H.B. Jones...
    P.557-561页
    查看更多>>摘要：Dental ceramics are attractive in restorative dentistry due to their approximations to the appearances and functions of human teeth with which we chew our food. Chewing processes generally occur at cyclic loading range of 70-800 N and up to 1400 cycles per day. Most fatigue studies on dental ceramics were conducted at the loads up to 250 N. These loads are much smaller than the maximum bite forces of 500-700 N and tooth clench or grinding forces of up to 800 N. This paper reports on an investigation of fatigue response of a dental porcelain at the higher end of the load range impacted by a tungsten carbide ball. The responses of surface roughness and contact stress to the applied loads and cyclic numbers were quantitatively studied. The results show that the cyclic numbers had significant influences on both average surface roughness Ra and maximum roughness Rmax (ANOVA, p<0.05). However, the applied loads did not significantly affect Ra and Rmax values (ANOVA, p>0.05). It is also found that the contact stress significantly reduced with the cycles (ANOVA, p<0.05) but did not show a significant change with the applied loads (ANOVA, p>0.05).
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    FEA-Predicted Subsurface Damage in Micro Finishing of a Feldspar Porcelain Using Fine-Grit Dental Burs

    Xiao-Fei SongLing Yin
    P.562-566页
    查看更多>>摘要：Biocompatible ceramic structures are used to replace missing teeth, tooth structure lost to disease or trauma, and un-aesthetic healthy, tooth enamel. Recreating aesthetics and function are the two practical goals of such restorative treatment. However, the failure rate of ceramic prostheses is relatively high due to their inherent brittleness. A primary reason to premature failure of ceramic prostheses is surface and subsurface damage induced in dental intraoral finishing using dental handpieces and abrasive burs. In this paper, finite element analysis (FEA) was applied to predict quantitatively finishing-induced stress fields and subsurface damage depths in dental porcelain surfaces using fine grit diamond burs. The results indicate that while finishing using fine diamond burs diminished subsurface damage, damage depths of smaller than 20 u.m remained depending on the bur depth of cut and feed rate. In the FEA modeling, the minimum damage was obtained under very fine finishing conditions.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Production, Characterization and Application of Silicon-on-sapphire Wafers

    Alokesh PramanikMei LiuL.C. Zhang
    P.567-572页
    查看更多>>摘要：Silicon-on-sapphire (SOS) thin film systems have had specific electronic applications because they can reduce noise and current leakage in metal oxide semiconductor transistors. However, there are some issues in producing defect-free SOS wafers. Dislocations, misfit, micro twins and residual stresses can emerge during the SOS processing and they will reduce the performance of an SOS product. For some reasons, research publications on SOS in the literature are not extensive, and as a result, the information available in the public domain is fragmentary. This paper aims to review the subject matter in an as complete as possible manner based on the published information about the production, characterization and application of SOS wafers.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    A Vacuum Sucking Approach to Preventing Chips from Attaching to Machined Surface in Cutting of KDP Crystals

    Ziwen ZhengHaofeng ChenYifan DaiHang Gao...
    P.573-581页
    查看更多>>摘要：Potassium Dihydrogen Phosphate (KDP) crystals are used for the key components in high power density solid-state laser for Inertial Confinement Fusion. KDP crystals are mainly machined in the dry cutting condition to avoid 'Fogging' of the crystals. The main difficulty identified in dry machining of KDP is chip removal from the machined surface. A vacuum sucking device based on venturi vacuum pump is used to suck the chips during cutting, and the relationship between level of vacuum in cutting zone and the comply air pressure was established. An empirical model for chip emission during turning processes is used to analyze the influence of cutting parameters on the chip emission. The influence of cutting parameters on the removal of chips is investigated. Finally, a face turning of KDP crystals is carried out with the turning parameters of feed rate lum/rev, depth of cut of 0.8 um/rev and the cutting speed from 1.82m/s to 3.9m/s. A super-smooth surface with chips free in the whole sample is achieved, having the surface roughness of 2.994nm (Ra) measured by AFM. The surface quality achieved satisfies the requirements of KDP crystals implemented in high power lasers.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Critical Undeformed Chip Thickness and Cutting Pressure in Relation to Ductile Mode Cutting of KDP Crystal

    Haofeng ChenZiwen ZhengYifan DaiHang Gao...
    P.582-587页
    查看更多>>摘要：Microgroove processes are carried out on Potassium Dihydrogen Phosphate (KDP) crystals of different crystalline orientation using diamond tool, the speed of groove is very low in order to avoid the influence of temperature. The main process characteristics are examined including the groove geometry, cutting forces and critical underformed chip thickness at the onset of ductile-to-brittle cutting transition. Additionally, the cutting pressure is calculated from the cutting force and grooving geometry. The experimental results show that as the groove depth increase, the groove geometry clearly revealed that ductile-to-brittle cutting transition occurred, and the transition are well reflected by changing in the cutting pressure. Further, it is shown that the critical undeformed chip thickness varies greatly with the workpiece KDP crystalline orientation.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Influence of the Workpiece Crystallographic Orientation on Ultra-Precision Turning of KDP Crystals

    Ziwen ZhengHang GaoXiaoping Li
    P.588-595页
    查看更多>>摘要：The mechanical properties of Potassium Dihydrogen Phosphate (KDP) crystal had been relatively well investigated, and it was reported that mechanical properties of KDP crystal are anisotropic corresponding to crystallography orientation. However, the affect of the crystallography orientation to the critical undeformed chip thickness and cutting force variation in ductile mode cutting of KDP crystal are still not clear, which are important in determining proper cutting parameters to get fine finished surface. This paper investigates the influence of crystallographic orientation to critical undeformed chip thickness by a kind of groove cutting on {001} plane, and the influence to cutting force is also researched by face turning. The experiment results demonstrate that the cutting forces and critical undeformed chip thickness for ductile mode cutting varies greatly according to KDP crystallographic orientation. This paper point out that two slipping plane, {110} and {110}, account for the variation of cutting force and critical undeformed chip thickness in different orientation on {001} plane. A set of cutting parameters for ductile mode cutting are selected based on the derived critical undeformed chip thicknesses at different crystal orientations, and overall sooth surface has been achieved on face turned {001} surface, which the roughness is Ra 2.6nm measured by Veeco white-light interferometer.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Some Aspects of Improving Integrity of Machined Surfaces on Al/SiCp Metal Matrix Composites

    Uday A. DabadeSuhas S. Joshi
    P.596-601页
    查看更多>>摘要：This paper presents findings of an experimental work which involved use of wiping edge on the cutting tool and a priory heating of the work surfaces to improve the integrity of machined surfaces. The wiper edge cleans the machined surface and a priory heating induces necessary local ductility into the machined surface to promote improvement in the surface integrity. The result shows that the wiper inserts reduce surface roughness (by about 38%); cutting forces (by about 8%) and induce compressive (or lower tensile) residual stresses in the machined surfaces, hence help to improve the surface integrity. Similarly, a priory heating of work surfaces at 70℃ was also found to improve machined surface roughness considerably.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd