Fabrication of diamond/W – Cu functionally graded material by microwave sintering

Chenlong Wei,Jigui Cheng,Mei Zhang,Rui Zhou,Bangzheng Wei,Xinxi Yu,Laima Luo,Pengqi Chen 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.3

A four-layered W/Cu functionally graded material (FGM) (W90% þ Cu10%/W80% þ Cu20%/W70% þ Cu30%/W60% þ Cu40%, wt.% fraction) and a four-layered diamond/WeCu FGM (W90% þ Cu10%/W80% þ Cu20%/W70% þ Cu30%/W55% þ Cu40% þ diamond5%, wt.% fraction) were fabricated by microwavesintering. The thermal conductivity and thermal shock resistance of diamond/WeCu FGM andWeCu FGM were investigated. The morphologies of the diamond particles and different FGMs wereanalyzed using AFM, SEM, EDS, and TEM. The results show that a 200 nm rough tungsten coating wasformed on the surface of the diamond. The density of the tungsten-coated diamond/WeCu FGM, obtainedby microwave sintering at 1200 C for 30 min, was 94.66%. The thermal conductivity of the fourlayereddiamond/WeCu FGM was 220 W$m-1$K-1, which is higher than that of the four-layered W/CuFGM (209 Wm 1 K 1). This indicates that adding an appropriate amount of tungsten-coated diamond tothe high Cu layer W/Cu FGM improves the thermal conductivity of the composite. The diamond/WeCuFGM sintered at 1200 C for 10 min exhibited better thermal shock resistance than diamond/WeCu FGMsintered at 1100 C for 10 min

금속사출성형을 위한 W-10wt.%Cu 분말의 제조에 관한 연구

김순욱,손찬현,김영도,문인형 한국분말야금학회 2001 한국분말재료학회지 (KPMI) Vol.8 No.4

Recent remarkable progress in the semiconductor industry has promoted smaller size of semiconductor chips and increased amounts of heat generation. So, the demand for a substrate material to meet both the characteristics of thermal expansion coefficient and heat radiation has been on the increase. Under such conditions, tungsten(W)-copper(Cu) has been proposed as materials to meet both of the above characteristics. In the present study, the W-10wt.%Cu powders were synthesised by the mixing and hydrogen reduction of the starting mixture materials such as W-Cu, $W-CuCl_2$and $WO_3-CuCl_2$ in order to obtain the full densification. The W-10wt.%Cu produced by hydrogen reduction showed the higher interparticle friction than the simple mixed W-10wt%Cu because of the W agglomerates. In the dilatometric analysis the W-10wt.%Cu prepared from the $W-CuCl_2$was largely shrank by heating up $1400^{\circ}C$ at the constant heating rate of $5^{\circ}C$/min. The possibility of application of metal injection molding (MIM) was also investigated for mass production of the complex shaped W-Cu parts in semiconductor devices. The relationship between the temperature of molding die and the pressure of injection molding was analyzed and the heating up stage of 120-$290^{\circ}C$ in the debinding process was controlled for the most suitable MIM condition.

Continuous W Cu functional gradient material from pure W to W Cu layer prepared by a modified sedimentation method

Wei Bangzheng,Zhou Rui,Xu Dang,Chen Ruizhi,Yu Xinxi,Chen Pengqi,Cheng Jigui 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.12

The thermal stress between W plasma-facing material (PFM) and Cu heat sink in fusion reactors can be significantly reduced by using a WeCu functionally graded material (WeCu FGM) interlayer. However, there is still considerable stress at the joining interface between W and WeCu FGM in the W/WeCu FGM/Cu portions. In this work, we fabricate W skeletons with continuous gradients in porosity by a modified sedimentation method. Sintering densification behavior and pore characteristics of the sedimented W skeletons at different sintering temperatures were investigated. After Cu infiltration, the final WeCu FGM was obtained. The results indicate that the pore size and porosity in the W skeleton decrease gradually with the increase of sintering temperature, but the increase of skeleton sintering temperature does not reduce the gradient range of composition distribution of the final prepared WeCu FGM. And WeCu FGM with composition distribution from pure W to W-20.5wt.% Cu layer across the section was successfully obtained. The thickness of the pure W layer is about one-fifth of the whole sample thickness. In addition, the prepared WeCu FGM has a relative density of 94.5 % and thermal conductivity of 185 W/ (m K). The WeCu FGM prepared in this work may provide a good solution to alleviate the thermal stress between W PFM and Cu heat sink in the fusion reactors.

Enhancement of Microstructural Homogeneity of W-Cu Pseudo-alloy by Adding W-Cu Composite Powder in Infiltration Process

Hong Moon-Hee,Choi Jae-Ho,Lee Seong,Kim Eun-Pyo,Noh Joon-Woong,Lee Sung-Ho,Kim Young-Moo 한국분말야금학회 2006 한국분말야금학회 학술대회논문집 Vol.2006 No.1

An infiltration technique using W-Cu composite powder has been developed to enhance microstructural uniformity of W-Cu pseudo-alloy. W-Cu composite powder, manufactured by reduction from WO3 and CuO powder mixtures, were blended with W powder and then cold iso-statically pressed into a cylindrical bar under 150 MPa. The pressed samples were pre-sintered at 1300 oC for 1 hour under hydrogen to make a skeleton structure. This skeleton structure was more homogeneous than that formed by using W and Cu powder mixtures. The skeleton structures were infiltrated with Cu under hydrogen atmosphere. The infiltrated W-Cu pseudo-alloy showed homogeneous microstructure without Cu rich region.

W-CuO 혼합물을 이용하여 제조된 W-Cu나노복합분말의 미세구조와 소결거동에 관한 연구

김길수,김대건,김영도 한국분말야금학회 2003 한국분말재료학회지 (KPMI) Vol.10 No.4

Recently, the fabrication process of W-Cu nanocomposite powders has been researched to improve the sinterability by mechanochemical process (MCP), which consists of ball milling and hydrogen-reduction with W- and Cu-oxide mixture. However, there are many control variables in this process because the W oxides are hydrogen-reduced via several reduction stages at high temperature over 80$0^{\circ}C$ with susceptive reduction conditions. In this experiment, the W-15 wt%Cu nanocomposite powder was fabricated with the ball-milling and hydrogen-reduction process using W and CuO powder. The microstructure of the fabricated W-Cu nanocomposite powder was homogeneously composed of the fine W particles embedded in the Cu matrix. In the sintering process, the solid state sintering was certainly observed around 85$0^{\circ}C$ at the heating rate of 1$0^{\circ}C$/min. It is considered that the solid state sintering at low temperature range should occur as a result of the sintering of Cu phase between aggregates. The specimen was fully densified over 98% for theoretical density at 120$0^{\circ}C$ for 1 h with the heating rate of 1$0^{\circ}C$/min.

Effect of ball-milling time on structural characteristics and densification behavior of W-Cu composite powder produced from WO₃-CuO powder mixtures

Ryu, S.S.,Park, H.R.,Kim, Y.D.,Hong, H.S. MPR Pub. Services 2017 International journal of refractory metals & hard Vol.65 No.-

<P>Understanding the microstructure of W-Cu nanocomposite powder is essential for elucidating its sintering mechanism. In this study, the effect of milling time on the structural characteristics and densification behavior of W-Cu composite powders synthesized from WO3-CuO powder mixtures was investigated. The mixture of WO3 and CuO powders was ball-milled in a bead mill for 1 h and 10 h followed by reduction by heat-treating the mixture at 800 degrees C in H-2 atmosphere with a heating rate of 2 degrees C/min to produce W-Cu composite powder. The microstructure analysis of the reduced powder obtained by milling for 1 h revealed the formation of W-Cu powder consisting of W nanoparticle-attached Cu microparticles. However, Cu-coated W nanocomposite powder consisting of W nanoparticles coated with a Cu layer was formed when the Mixture was milled for 10 h. Cu-coated W nanopowder exhibited an excellent sinterability not only in the solid-phase sintering stage (SPS) but also in the liquid-phase sintering stage (LPS). A high relative sintered density of 96.0% was obtained at 1050 degrees C with a full densification occurring on sintering the sample at 1100 degrees C. The 1 h-milled W-Cu powder exhibited a high sinterability only in the LPS stage to achieve a nearly full densification at 1200 degrees C. (C) 2016 Elsevier Ltd. All rights reserved.</P>

W 입자크기가 W-Cu 복합재료의 전기 및 열전도도에 미치는 영향

양주환,오승탁,박상우,문인형 한국분말야금학회 2004 한국분말재료학회지 (KPMI) Vol.11 No.1

The electrical and thermal conductivity of W-Cu composites were investigated as a function of the W-particle size and W-W contiguity. Powder mixtures were prepared by ball milling or mechanical alloying process, and then sintered at various temperatures. The electrical conductivity of sintered composite was increased with decreasing W grain size. Dependence of electrical conductivity on the W grain size was explained by the W-W contiguity concept. The thermal conductivity was increased with increasing the temperature up to $600^{\circ}C$ but decreased at the temperature above $600^{\circ}C$ Also, thermal conductivity value was influenced by the W particle size. Change of thermal conductivity in W-Cu composites was discussed based on the observed microstructural characteristics and theoretical considerations.

W-Particle Shape in Liquid Cu during Heat Treatment of Cu-W Composite Powder Prepared by Mechanical Alloying

Suk, Myung-Jin,Hyun, Jin-Ho,Kim, Ji-Soon,Kwon, Young-Soon,Kim, Young Do 대한금속학회 2002 METALS AND MATERIALS International Vol.8 No.4

The equilibrium morphology of W-particles in liquid Cu was observed to be spherical (nonfaceted). When W and Cu were subjected to mechanical alloying treatment, the morphology of the W-particle in contact with liquid Cu was faceted. With prolonged heat treatment, the W-particle gradually became nonfaceted in morphology. The time needed to attain the equilibrium nonfaceted morphology depends on the duration of the mechanical alloying process. The present paper describes the morphological variation in the W-particle in liquid Cu that occurs during the heat treatment of Cu-5wt.%W composite powder prepared by a mechanical alloying process. The effect of mechanical alloying treatment on the morphology of the W-particle in contact with liquid Cu is discussed.

W-CU 복합재료의 전도도에 미치는 미세조직의 영향

이영중,박광현,이병훈,김덕수,김영도,Lee Young Jung,Park Kwang Hyun,Lee Byung Hoon,Kim Deok-Soo,Kim Young Do 한국재료학회 2005 한국재료학회지 Vol.15 No.2

[ $W-15wt.\%$ ] Cu nanocomposite powders are fabricated by ball-milling and subsequent hydrogen-reduction. The compacted parts of $W-15wt.\%Cu$ nanocomposite powders were sintered at $1200^{\circ}C$ for 1 h with various heating rates of 5 and $20^{\circ}C/min$. The homogeneity of the sintered microstructures was evaluated through homogeneity index by the standard deviation of Victor's hardness test. The W-W contiguities were calculated by using Voronoi diagrams. The sintered microstructure with the heating rate of $20^{\circ}C/min$ was more homogeneous and had lower W-W contiguity than that of $5^{\circ}C/min$. The microstructural homogeneity was directly related to the W-W contiguity. Thermal conductivity of the sintered parts with the heating rate of $20^{\circ}C/min$ was higher than that with heating rate of $5^{\circ}C/min$. This phenomenon indicates that the thermal conductivity is affected by the W-W contiguity resulting from the homogeneity of the sintered microstructure.

Microstructural Feature of Full-densified W-Cu Nanocomposites Containing Low Cu Content

Lee, Jai-Sung,Jung, Sung-Soo,Choi, Joon-Phil,Lee, Geon-Yong The Korean Powder Metallurgy Institute 2013 한국분말재료학회지 (KPMI) Vol.20 No.2

The microstructure evolution during sintering of the W-5 wt.%Cu nanocomposite powders was investigated for the purpose of developing a high density W-Cu alloy. The W-5 wt.%Cu nanopowder compact, fully-densified during sintering at 1623 K, revealed a homogeneous microstructure that consists of high contiguity structures of W-W grains and an interconnected Cu phase located along the edges of the W grains. The Vickers hardness of the sintered W-5 wt.%Cu specimen was $427{\pm}22$ Hv much higher than that ($276{\pm}19$ Hv) of the conventional heavy alloy. This result is mostly due to the higher contiguity microstructure of the W grains compared to the conventional W heavy alloy.