Electrical Discharge Machining of Alumina-Zirconia-TiC Composites with Varying Zirconia Content
Electrical Discharge Machining of Alumina-Zirconia-TiC Composites with Varying Zirconia Content
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不同氧化锆含量的氧化铝-氧化锆-TiC复合材料的放电加工
DOI：
10.4028/www.scientific.net/kem.554-557.1916
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
R. Gadow
中科院分区：
文献类型：
--
作者：
R. Landfried;F. Kern;R. Gadow
陶瓷注射成型（CIM）或挤出需要具有高硬度的模具和压模，以减少由于加工高研磨性陶瓷化合物而发生的工具磨损。除了耐磨性之外，模具材料还需要高强度和韧性以承受应用期间的载荷。作者最近的工作表明，基于氧化物陶瓷基体的电火花可加工陶瓷复合材料在高磨损应用中具有很高的潜力。使用氧化铝-氧化锆复合材料（AZC）作为导电复合材料的基体使得能够将氧化铝的高硬度和氧化锆的高强度和韧性相结合，以定制模具材料的性能。本研究的重点是开发艾德可加工的AZC，碳化钛作为导电相。基质的组成从纯氧化铝到纯氧化锆在5个步骤中变化。采用热压法制备了用于机械和电性能表征及电火花加工实验的夹具。结果表明，从纯氧化铝基体的四点抗弯强度为430 MPa，硬度为2250 HV 10，韧性为3.7 MPa·m ~（-1）到纯氧化锆基体的四点抗弯强度为1020 MPa，硬度为1490 HV 10，韧性为5.9 MPa·m ~（-1），硬度、强度和韧性与成分几乎呈线性相关。基体成分的变化也导致显著不同的电火花加工特性。材料去除率在19体积%时显示出最大值氧化锆和58体积%氧化铝，而加工的复合材料的表面粗糙度显着降低与氧化锆量的增加。SEM和EDX分析，以确定每个陶瓷基体相的去除机制。据发现，氧化铝往往被除去的蒸发，由于放电。具有比氧化铝更高的熔点和汽化点的氧化锆在等离子体通道的形成期间熔化。氧化锆不能从表面完全去除，但在样品和电极上形成光滑和致密的再固化材料的无定形层。
Ceramic injection molding (CIM) or extrusion requires molds and dies with high hardness to reduce tool wear which occurs due to processing of highly abrasive ceramic compounds. Besides the wear resistance high strength and toughness are necessary for mold materials to withstand the loads during application. Recent work of the authors has shown the high potential of electrical discharge machinable ceramic composites based on oxide ceramic matrices for high wear applications. The use of alumina zirconia composites (AZC) as matrix for electrically conductive composites enables the combination of high hardness of alumina and high strength and toughness of zirconia in order to customize the properties of the mold material. This study focuses on development of ED machinable AZCs with addition of 24 vol.-% titanium carbide as electrically conductive phase. The composition of the matrix was varied from pure alumina to pure zirconia in 5 steps. Disks for mechanical and electrical characterization and electric discharge machining experiments were manufactured by hot pressing. Results show that hardness, strength and toughness can be almost linearly correlated to composition from pure alumina matrix with a 4-point bending strength of 430 MPa, a hardness of 2250 HV10 and a toughness of 3.7 MPa√m to pure zirconia matrix with 1020 MPa bending strength, 1490 HV10 and a toughness of 5.9 MPa√m. Variation of matrix composition also leads to significantly different EDM characteristics. The material removal rate shows a maximum at 19 vol.-% zirconia and 58 vol.-% alumina while surface roughness of the machined composites decreases significantly with increasing zirconia amount. SEM and EDX analysis were made to identify removal mechanisms of each ceramic matrix phase. It was found that alumina tends to be removed by vaporization due to electrical discharges. Zirconia, which has a higher melting and vaporization point than alumina melts during the formation of the plasma channel. Zirconia cannot be removed in total from the surface but forms a smooth and compact amorphous layer of resolidified material on both sample and electrode.