The evaluation of W/ZrC composite fabricated through reaction sintering of two precursors: Conventional ZrO2/WC and novel ZrSiO4/WC

In this study the W-ZrC composites fabricated by in situ reaction sintering of two precursors were compared, 1-The conventional WC and ZrO₂ which are ball milled with established molar ratio of 3–1 for 12 hours, gelcasted to form a green body and then undergo a pressure less sintering cycle, 2-A new and innovative way in which for the first time ZrSiO₄ was used instead of ZrO₂, and by testing different molar ratio between WC and ZrSiO₄ it was understood that the optimum ratio is 3–1 once again. Furthermore the starting ZrO₂ and ZrSiO₄ powder were selected in nano size and it was understood that by using nano powders the amount of unreacted and unwanted phase reduce, the reaction progress and the mechanical proprieties improve. Although the reaction sintered WC/ZrO₂ possess better properties, regarding the cost considerations, reaction sintering of WC/ZrSiO₄ is a much cheaper process.     

超高温热处理对不同工艺制备的W/ZrC金属陶瓷微观组织结构的影响

分别采用置换填充工艺（DCP）和热压烧结工艺（HP）制备了W/ZrC金属陶瓷,然后在2600℃下对其进行热处理1h,研究了热处理前后两种W/ZrC金属陶瓷的组织结构变化。研究表明热处理后两种材料都出现开孔率增大、线膨胀及质量损失。其中DCP法W/ZrC金属陶瓷在热处理后仍由分散分布的W颗粒相和连续的ZrC相组成,但原始材料中残留的WC、W2C及Zr-Cu合金相都消失,取而代之的是大量的空隙,同时W相含量也急剧减小。而HP法W/ZrC金属陶瓷在热处理后则有新相W2C生成,同时其W颗粒相有聚集的趋势,形成了大块团状相。     

Process optimization,microstructures and mechanical/thermal properties of Cu/Invar bi-metal matrix composites fabricated by spark plasma sintering

An orthogonal experiment scheme was designed to investigate the effects of the Cu content, compaction pressure, and sintering temperature on the microstructures and mechanical and thermal properties of (30–50)wt.%Cu/ Invar bi-metal matrix composites fabricated via spark plasma sintering (SPS). The results indicated that as the Cu content increased from 30 to 50 wt.%, a continuous Cu network gradually appeared, and the density, thermal conductivity (TC) and coefficient of thermal expansion of the composites noticeably increased, but the tensile strength decreased. The increase in the sintering temperature promoted the Cu/Invar interface diffusion, leading to a reduction in the TC but an enhancement in the tensile strength of the composites. The compaction pressure comprehensively affected the thermal properties of the composites. The 50wt.%Cu/Invar composite sintered at 700 °C and 60 MPa had the highest TC (90.7 W/(m·K)), which was significantly higher than the TCs obtained for most of the previously reported Cu/Invar composites.     

W/ZrC复合材料的反应熔渗法制备

采用W/WC多孔预制体中低温熔渗Zr2Cu合金的方法成功制备了W/ZrC复合材料.结果表明:与传统粉末冶金方法相比,制备温度降低了500℃左右.复合材料的组织均匀,致密度较高;抗弯强度和弹性模量分别可达600MPa和360 Gpa:断裂韧性达11.0 Mpa·m1/2,比纯ZrC的断裂韧性提高了4倍.     

DCP法W/ZrC金属陶瓷组成结构的高温演变研究

采用置换填充工艺制备了W/ZrC金属陶瓷,研究了其在不同超高温温度环境中的组成结构演变规律。结果表明：随着热处理温度的升高,材料的质量损失率先增大后减小,在2200 ℃时有最大值2.05 wt.%,而孔隙率则不断增大,在2600 ℃时达到9.29 vol.%。在材料表面,残留Cu最先熔化挥发流失,其次残留Zr,在2600 ℃时部分ZrC也分解流失。在材料内部,1800 ℃时未反应完的WC相消失,2200 ℃时残留Zr-Cu合金相和W2C相消失,2600 ℃时仅剩下W相和ZrC相,且随着热处理温度的升高,W原子向ZrC基体中的扩散增多,导致ZrC点阵常数逐渐减小,W相由颗粒状变为无规则的长条状,其颗粒数量和体积含量明显减少,并形成了大量闭孔。Zr-Cu合金的流失和W原子的扩散是引起W/ZrC金属陶瓷在超高温环境中组织结构变化的重要原因。     

Preparation of nanosized W／Cu composite powder by sol-gel technique

1 Introduction W/Cu alloys have been widely used in variousapplications, such as welding electrodes, heat sinks and spreaders due to their high thermal and electrical conductivity, high arc erosion and low thermal ex-pansion coefficient [1-2]. There are t…     

Microstructures and properties of Cu/Ag(Invar) composites fabricated by powder metallurgy

The Ag (Invar) composite powder prepared by ball milling was used to fabricate the Cu/Ag (Invar) composites. Microstructures and properties of the composites were studied after sintering and thermo-mechanical treatment. The results indicate that during ball milling, micro-forging weld and work-hardening fracture result in that the average particle size of the Ag (Invar) powder increases rapidly at first, and then decreases sharply, finally tends to be constant. Compared with the Cu/Invar ones, the sinterability of the composites is greatly improved, resulting in that the pores in them are smaller in amount and size. After the thermo-mechanical treatment, the Cu/Ag (Invar) composites are nearly fully dense with the optimum phase composition and element distribution. More importantly, Cu and the Invar alloy in the composites distribute continuously in a three-dimensional (3D) network structure. Cu/Invar interface diffusion is effectively inhibited by the Ag barrier layer, leading to a great improvement of the mechanical and thermal properties of the Cu/Ag (Invar) composites.     

钨粉化学镀铜对W／15Cu电子封装材料性能的影响

采用化学镀铜的方法在钨粉中加入诱导铜，经压型，熔渗后制成W／15Cu合金。用扫描电镜研究了材料的显微结构，并测出合金样品的密度、气密性、热膨胀系数等物理性能，通过与传统工艺制备的W／15Cu合金的显微组织以及物理性能方面做比较，讨论了钨粉化学镀铜对W／15Cu合金性能的影响。结果表明，钨粉化学镀铜对于提高钨生坯成形性能、改善钨铜复合材料的显微组织结构、提高材料物理性能方面都有很大作用。经过综合比较，镀铜含量以2％为宜。     

纤维结构W/Cu触头材料电弧烧蚀性能的研究

研究了W／Cu系列触头材料的电弧烧蚀性能。在相同条件下，对粉末冶金W／Cu触头材料及纤维结构的W／Cu触头材料电弧烧蚀性能以及不同直径纤维结构的W／Cu触头材料电弧烧蚀性能进行了对比。研究发现细纤维结构的W／Cu触头材料抗电弧烧蚀性能最好。     

碳/铜复合材料摩擦磨损性能的研究

将用机械合金化法制备的碳/铜复合材料粉末进行放电等离子烧结。对烧结后的样品进行了摩擦磨损性能研究。结果表明,复合材料的摩擦系数均随含碳量的增加呈下降趋势;当碳含量为6%时,磨损率最低。     

镁合金表面沉积铜钨复合涂层工艺及涂层性能研究

目的提高镁合金表面的耐蚀耐磨性。方法采用冷喷涂与化学气相沉积(CVD)相结合的方法在镁合金表面制备出Cu/W复合涂层,并对复合涂层的结构、成分、组织形貌、耐磨性、耐蚀性、结合力进行分析。结果镁合金基体沉积Cu/W复合涂层后,表面硬度提高了687.1HV,磨损率从0.032%降到0.020%,腐蚀电位正移了1.3 V,临界载荷相比直接化学气相沉积W涂层提高了120.5 N。结论Cu/W复合涂层显著提高了镁基体的耐磨、耐蚀性,涂层与基体结合力较高。     

等离子喷涂ZrC涂层耐烧蚀性能与机理研究

采用等离子喷涂工艺在C/SiC基体材料表面制备了较为致密的W粘结层和ZrC耐烧蚀涂层,利用氧乙炔火焰测试其抗烧蚀性能。结果表明:涂层具有良好的抗烧蚀性能。经烧蚀距离30 mm的氧乙炔烧蚀300 s后,涂层的质量烧蚀率为1.7×10~(-3)g·s~(-1),仅为无涂层试样的68%;线烧蚀率为4.0×10~(-4)mm·s~(-1),仅为无涂层试样的30%。随着烧蚀距离的减小,涂层的质量烧蚀率不断增大,线烧蚀率不断减小。试样表面温度梯度导致涂层存在3种典型烧蚀形貌,中心致密区,过渡区以及边缘疏松区。温度较高的中心区氧化产物为WO_3,其发生熔融并填充涂层内部孔隙和裂纹,形成致密层,且与ZrO_2所产生的协同效应有效降低了机械剥蚀几率,烧蚀以热化学烧蚀为主;温度较低的边缘区烧蚀产物未发生熔融且呈现疏松状,烧蚀主要表现为热化学烧蚀和机械剥蚀。     

Cu/Al/Cu层状金属复合材料电子束焊接接头特征

研究了Cu/Al/Cu层状金属复合材料的电子束焊,对焊接接头的表面成形、微观组织、力学性能进行分析。结果表明,采用电子束焊可以实现Cu/Al/Cu层状金属复合材料的有效连接。不同金属层焊缝宽度明显不同,铝层焊缝宽度最大,且铝层金属大量进入顶部和底部的铜层焊缝中。各层母材和焊缝界面均出现了IMCs层,铝层主要是Al2Cu,铜层则主要是AlCu,Al2Cu。在焊缝中心生成大量的块状Al2Cu,均匀分布在α-Al和Al2Cu组成的共晶组织基体中。接头抗拉强度为44 MPa,断口呈现明显的脆性断裂特征,拉伸断裂位置于显微硬度最高的焊缝中心区。创新点： (1)采用Cu/Al/Cu层状金属复合材料代替纯铜在工业领域的应用。(2)采用电子束焊接技术实现Cu/Al/Cu三明治结构层状金属复合材料的焊接。     

Feasibility study of electrical discharge machining for W/Cu composite

This study investigates the feasibility and optimization of electrical discharge machining for inspecting the machinability of W/Cu composites using the Taguchi method. W/Cu composites are a type of cooling material highly resistant to heat corrosion produced through powder metallurgy. As W/Cu composites are highly brittle, they are not suited to be machined of traditional machine manufacturing. This paper utilizes electrical discharge machining, which is thermal processing workpieces and not affected by mechanical properties of materials. This experiment utilizes the Taguchi method and L₁₈ orthogonal table to obtain the polarity, peak current, pulse duration, duty factor, rotary electrode rotational speed, and gap-load voltage in order to explore the material removal rate, electrode wear rate, and surface roughness. The influence of each variable and optimal processing parameter will be obtained through ANOVA analysis and verified through experimentation to improve the process. The final step is to study the surface integrities of W/Cu composite, such as surface profile and heat-affected zone, the energy distribution transferring phenomenon of W/Cu composite, and the discharge phenomenon of tungsten and copper elements with electrical discharge machining.     

W/Cu功能梯度材料的制备及应用

W/Cu功能梯度材料性能优异应用广泛,以W/Cu功能梯度材料的制备方法为研究对象,探讨不同制备方法存在的优缺点,包括熔渗法、粉末冶金法及等离子喷涂法。作为等离子体材料应与等离子体相适应,耐热冲蚀。在电子领域中,其一侧应满足与基板的封接问题,另一侧满足高导热、低热膨胀系数的要求。目前虽然研发出多种新工艺、新技术,但需进一步了解其控制因素及影响机理,另外每种工艺适用范围比较小,需开发高效、低成本、适用广、易控制的制造工艺。     

纤维结构W/Cu触头材料的制备

采用织网叠层法,以钨丝为纬线,铜丝为经线编织二维网,将网与铜坯叠放在一起,于真空烧结炉中熔渗的真空熔渗工艺制备纤维结构W/Cu触头材料。试验给出了该工艺的主要工艺参数。与粉末冶金制造的W/Cu触头材料的烧蚀性能作对比,从触头表面在电弧烧蚀后的熔层形貌分析表明,纤维结构W/Cu触头材料呈现较好的抗烧蚀特性。     

ZrC_p/W复合材料的烧蚀性能

用自制的氧乙炔烧蚀装置对ＺｒＣｐ／Ｗ复合材料烧蚀性能进行了研究。结果表明：复合材料的质量烧蚀率和线烧蚀率由低到高的排列顺序为 ４０％ＺｒＣｐ（体积分数,下同）／Ｗ＜３０％ＺｒＣｐ／Ｗ＜Ｗ;钨中加入ＺｒＣ颗粒明显提高了钨的抗烧蚀性能,而且 ＺｒＣ颗粒含量越高,材料抗烧蚀性能越好。并用多波长高温计对烧蚀表面温度进行在线测试。复合材料烧蚀机理是Ｗ,ＺｒＣ的氧化烧蚀。     

Microstructure,phase transformation and mechanical properties of NiMnGa particles/Cu composites fabricated by SPS

Microstructure, phase transformation and mechanical properties of NiMnGa particles/Cu composites prepared by spark plasma sintering method were investigated by SEM, EDS, XRD, susceptibility measurements and mechanical tests. The NiMnGa particles were found to react with Cu matrix and the composites exhibited a similar crystal structure to the Cu matrix. The martensitic transformation and Curie transition of the composites were weakened due to the composition change of NiMnGa particles caused by reactions. With increasing NiMnGa particles content, the martensitic transformation and Curie transition of the composites were enhanced to some extent. However, the martensitic transformation temperature and Curie transition temperature were decreased by ~50 K as compared to those of the original NiMnGa particles. The compressive strength of the composites increased with the increase of NiMnGa particles content, whereas the compressive strain was decreased gradually.     

挤压铸造法制备高致密Mo/Cu及其导热性能

采用专利挤压铸造方法制备了3种Mo体积分数分别为55%、60%和67%的Mo/Cu复合材料,并对其微观组织和导热性能进行了研究.结果表明:Mo颗粒分布均匀,Mo/Cu界面干净,不存在任何界面反应物和非晶层;复合材料组织均匀、致密,且致密度高达99%以上;复合材料的热导率为220～270 W/(m·K),并随着Mo含量的增加而降低.混合定律(ROM)较好地预测了55%Mo/Cu复合材料的热导率,而采用Maxwell模型和H-M模型的计算值与60%和67%Mo/Cu复合材料的热导率测试值一致.     

化学镀和粉末冶金法制备W/Cu梯度热沉材料

用化学镀法和粉末冶金的方法制备高致密的W/Cu梯度热沉材料。用场发射扫描电镜观察了材料的组织结构、界面和断口形貌。对材料的机械性能也进行了表征,如抗弯强度和显微硬度。结果表明材料每一层都很致密且组织结构均匀。从截面上材料成分呈梯度分布,每层之间没有明显的界面。三层W/Cu梯度热沉材料的相对密度可达99.2%。散热层、过渡层和封接层的显微硬度值分别是200、210和240 HV。抗弯实验结果所示封接层和散热层作为承重抗弯表面时的抗弯强度分别是428.5MPa和480.7MPa。