原位反应法制备Al2O3-TiC/Al复合材料

通过向含Ti的Al-Si合金熔体中通入CO2气体制备Al2O3-TiC／Al复合材料的方法．研究了Al2O3-TiC／Al复合材料特性。用X射线衍射仪（XRD）、扫描电子显微镜（SEM）和透射电子显微镜（TEM）对复合材料的组织进行了研究。研究表明，CO2与合金熔体中的Al、Ti原位反应生成Al2O3和TiC颗粒，Al2O3和TiC颗粒尺寸在0．2～1．0μm之间，均匀分布在基体中，反应生成的Al2O3和TiC颗粒数量与CO2的通入时间有关。     

不同球磨法对SPS制备Al2O3-TiC复合材料的影响

以Al2O3,Ti,和C(石墨)为原料,分别采用高能球磨原位反应和行星球磨湿混处理原料粉末,再都结合放电等离子体烧结技术(SPS)制备了的Al2O3-TiC复合材料,并用XRD,OM和SEM分析了复合材料的相组成和显微结构.结果表明高能球磨原位合成的粉末烧结活性高,烧结体晶粒均一细小(＜300 nm),致密度高(98.9%),两相分布均匀;而经过行星球磨湿混处理的粉体,由于存在混合均匀性问题,反应进行的不完全,导致难以致密.高能球磨能促进晶粒细化,弥散分布均一化,反应进行完全和烧结致密化.     

原位Al2O3颗粒增强铜基复合材料的制备及微观组织

采用原位反应的方法成功制备了Al2O3颗粒增强铜基复合材料.对原位反应过程进行了热力学分析和动力学分析.SEM观察和EDS分析显示,原位反应生成的Al2O3颗粒分布于Cu基体中,且颗粒平均直径约为0.5μm,在材料中平整圆滑的Al2O3颗粒与基体结合良好.     

可加工性BN/Al2O3陶瓷基复合材料的制备

利用气相化学反应, 以H3BO3和CO(NH2)2作为BN源, 将纳米BN包覆到Al2O3颗粒表面, 经热压烧结制备出高强韧可加工BN/Al2O3复合材料. 材料的三点弯曲强度随BN含量的增加而缓慢降低, BN体积分数为30% 时, 仍达到446MPa; 断裂韧性随BN含量的增加而得到显著改善, 较单相氧化铝陶瓷提高近一倍. BN体积分数大于20%时, 该复合材料可用WC钻头在普通台式钻床上钻孔, 在小的轴向压力(10N)下, 钻孔速率大于1mm/min, 钻孔边缘平整, 没有崩裂现象, 内壁光滑, 粗糙度RZ =(6±0.5)μm. SEM观察显示, 加工未带来明显的损伤. 材料优异的力学性能及可加工性源自于基质中均匀分布的细小h-BN的颗粒增韧机制及其易解理的层状结构特点.     

Cutting performance and wear mechanism of nanoscale and microscale textured Al2O3/TiC ceramic tools in dry cutting of hardened steel

Nanoscale and microscale textures with different geometrical characteristics were fabricated on the surface of the Al₂O₃/TiC ceramic tool, and molybdenum disulfide (MoS₂) solid lubricants were burnished into the textures. The effect of the textures on the cutting performance was investigated using the textured self-lubricated tools and conventional tools in dry cutting tests. The tool wear, cutting force, cutting temperature, friction coefficient, surface roughness and chip topography were measured. Results show that the cutting force, cutting temperature, friction coefficient and tool wear of nanoscale and microscale textured self-lubricated tools are significantly reduced compared with the conventional tool, and the developed tool with wavy microscale textures on the rake face is the most effective in improving the cutting performance. The textured self-lubricated tools increase the surface roughness of machined workpiece, while they can reduce the vibration for a stable cutting and produce more uniform surface quality. The chip topography is changed by the textured self-lubricated tools. As a result, the nanoscale and microscale textured self-lubricated tools effectively improve the cutting performance of conventional Al₂O₃/TiC ceramic tool, and they are applicable to a stable dry cutting of the hardened steel.     

(Al_2O_3+Si)_p/Al系铝基复合材料的原位制备及性能

以Al-Si O2为体系,通过粉末冶金液相烧结的方法原位合成(Al2O3+Si)p/Al系铝基复合材料,利用XRD、DSC和SEM等测试技术测试了复合材料的相组成、密度、电导率及热膨胀性能,观察了Si相和Al2O3相的形貌并分析了相与相之间的反应界面。结果表明,通过该方法可以制备出具有优良性能的电子封装材料,其密度、电导率和热膨胀系数分别达到了2.5 g/cm3、10-7Ω·m和5×10-6/K。原位生成的Al2O3相多数呈圆球状颗粒,Si相以片状形成,随着烧结温度的提高,两种相和基体结合紧密,分布更加均匀分散,且无界面反应物生成。     

Fabrication of finegrained Al2O3 ceramic at low sintering temperature

A research on fabrication of finegrained Al2O3 ceramic at lower sintering temperature was carried out.Al2O3 powder with 50 nm in diameter is compounded with 11.24%Al and 4.75% Fe(mass fraction) by high-energy ball-milling. AI is got from Al powder which is a component of the materials being milled and Fe from steel milling balls and milling jar during the milling. In this way, nearly no impurity is brought into the composite powder during milling. With hot pressing of the composite powder and pure Al2O3 powder, it is proved that Al2O3 powder can be densified at lower sintering temperature when the powder is compounded in this way. Al2OC and AlFe form during sintering process of the composite powder. With the reactive sintering and multiphase sintering mechanisms, finegrained Al2O3 ceramic is fabricated at low sintering temperature.     

Al2O3-TiC复合陶瓷与不锈钢扩散钎焊接头组织分析

采用金相显微镜、扫描电镜和电子探针,观察了Al2O3-TiC复合陶瓷与Cr18-Ni8不锈钢扩散钎焊接头的组织形貌,分析了元素在接头中的分布情况和界面附近区域元素的扩散情况.试验结果表明,Ti-Cu-Ti中间层与陶瓷具有良好的反应能力,促进元素的相互扩散.Al2O3-TiC复合陶瓷与不锈钢扩散钎焊接头形成3个扩散反应层,其中一个位于Cr18-Ni8不锈钢侧,厚度约为17.5 μm,成分主要是Fe在β-Ti中的固溶体,Fe-Ti化合物和TiC;靠近陶瓷侧的反应层厚度约为7.5 μm,成分主要是TiC,Ti-O和Ti-Al;中间反应层厚度约为5μm,成分主要是Cu固溶体和Cu-Ti相.     

Effect of femtosecond laser pretreatment on wear resistance of Al2O3/TiC ceramic tools in dry cutting

A femtosecond pulsed laser (pulse width: 120 fs, wavelength: 800 nm and repetition rate: 500 Hz) was used for the pretreatment on the rake face of Al₂O₃/TiC ceramic cutting tools. The evolution of surface morphology of pretreated cutting tools irradiated with different pulse energies was measured by scanning electron microscope (SEM) and atomic force microscope (AFM). Dry cutting tests were carried out with these pretreated tools and conventional tools on hardened steel. The effect of pulse energy on the wear resistance of these pretreated tools was investigated. Results show that the cutting forces have no significant difference between laser pretreated tools and the conventional tool; the cutting temperatures of laser pretreated tools were slightly reduced compared with the conventional tool. Meanwhile, we found that the laser pretreated tools increased the adhesions of chips on the rake face, but they can significantly improve the wear resistance of the rake face; and laser pulse energy was found to have a profound effect on the wear resistance of the laser pretreated tools.     

Mechanical properties and microstructure of Al2O3/Ti(C,N)/CaF2@Al2O3 self-lubricating ceramic tool

Due to the poor mechanical properties of solid lubricants, direct addition to the ceramic matrix will reduce the mechanical properties of the material. In this study, Al(OH)₃ was coated on the surface of nano CaF₂ by non-uniform nucleation method and added to Al₂O₃/Ti(C,N) ceramic matrix. Al₂O₃/Ti(C,N)/CaF₂@Al₂O₃ was prepared by vacuum hot pressing sintering. Compared with the material directly added with nano-solid lubricant, the mechanical properties of ceramic tools added with coated nano-solid lubricant have been significantly improved. Among them, when the content of coated nano-solid lubricant is 10 vol%, the ceramic material has better comprehensive mechanical properties. SEM observation shows that the cross-sectional particle distribution of nano-coated powder ceramic material is relatively uniform and has good compactness. The fracture mode of ceramic materials is a mixed fracture mode of intergranular fracture and transgranular fracture.     

Rietveld法定量分析Al_2O_3-TiC复合陶瓷相含量

采用热压制备了纯Al2O3陶瓷和Al2O3-20wt%TiC复合陶瓷,引入XRD的Ri-etveld分析方法对纯Al2O3陶瓷和Al2O3-20wt%TiC复合陶瓷材料进行了定量相分析。通过Rietveld定量分析发现Al2O3-20wt%TiC复合陶瓷的相含量与原始粉末的配比基本一致。Rietveld方法的定量分析具有准确、高效和快捷等优点,此方法适用于复合陶瓷材料的定量分析。     

Mechanical property and cutting performance of yttrium-reinforced Al2O3/Ti(C,N) composite ceramic tool material

Effects of yttrium on the mechanical property and the cutting performance of Al₂O₃/Ti(C,N) composite ceramic tool material have been studied in detail. Results show that the addition of yttrium of a certain amount can noticeably improve the mechanical property of Al₂O₃/Ti(C,N) ceramic material. As a result, the flexural strength and the fracture toughness amount to 1010 MPa and 6.1 MPam^1/2, respectively. Cutting experiments indicate that the developed ceramic tool material not only has better wear resistance but also has higher fracture resistance when machining hardened #45 steel. The fracture resistance of the yttrium-reinforced Al₂O₃/Ti(C,N) ceramic tool material is about 20% higher than that of the corresponding ceramic tool material without any yttrium additives.     

Al2O3(p)/ZA35锌基复合材料的制备及其磨擦性能

利用Al2(SO4)3分解, 在铝熔体中原位生成Al2O3颗粒.实验结果表明: 采用石墨坩埚、电磁搅拌和铝熔体中加入镁的工艺流程, 可实现Al2O3颗粒和铝熔体的有效复合, 进而制备出Al2O3(p)/ZA35锌基复合材料; 与基体合金ZA35相比, 复合材料的耐磨减摩性能有了明显的提高.     

加工氧化锆陶瓷的金刚石涂层刀具的制备及切削试验研究

使用热丝化学气相沉积法(HFCVD)在硬质合金片以及球头铣刀表面沉积了微米金刚石薄膜(MCD),纳米金刚石薄膜(NCD)以及微米纳米复合金刚石薄膜(MNCD),通过扫描电子显微镜和拉曼光谱对其进行表征,结果呈现出典型的金刚石薄膜的性质,沉积质量高。金刚石薄膜与氧化锆陶瓷的摩擦磨损实验表明:金刚石薄膜能有效地降低对磨时的摩擦系数以及磨损率。使用三种金刚石薄膜涂层铣刀对氧化锆陶瓷进行铣削加工试验,结果显示:金刚石涂层刀具磨损率大幅度降低,刀具寿命显著增强。     

原位反应法制备A12O3/Al基复合材料的研究

利用原位反应制备了(Al2O3)p／Al复合材料，生成A1203颗粒分散度大．无聚集或偏聚现象，分布均匀。通过对反应所得材料的显微组织分析，(Al203)p与基体结台良好．界面无其他新相产生。试验证明：利用原位反应制备(Al203)p／Al复合材料．抗拉强度提高了25．6％，而伸长率仅下降了9％，在试验中加入Al2(SO4)3熔剂不仅细化Al2O3陶瓷颗粒，而且还起到辅助精炼和分散陶瓷相作用。     

激光熔覆纳米Al2O3等离子喷涂陶瓷涂层

采用X射线衍射仪、扫描电镜和显微硬度计研究了45#钢表面激光熔覆纳米Al2O3改性Al2O3 13%TiO2(质量分数)陶瓷涂层的相组成、微观结构和显微硬度,同时对涂层的磨损特性进行了考察.结果表明,激光重熔区亚稳相γ-Al2O3转变成稳定相α-Al2O3,熔覆层由粗颗粒α-Al2O3和TiO2以及纳米α-Al2O颗粒组成,在激光的作用下,等离子喷涂层的片层状结构得以消除; 纳米Al2O3颗粒仍然保持在纳米尺度,填充在涂层的大颗粒之间,使涂层致密化程度得以提高,因此纳米Al2O3改性涂层的显微硬度较高,且其耐磨性能明显优于等离子喷涂层.     

Fabrication of highly dense Al2O3 ceramics

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超微晶陶瓷氧化铝磨料的研究

本文首先分析了传统刚玉磨料和超微晶陶瓷氧化铝磨料的特点。以A l2O3.H2O和HNO3为原料、Zn(NO3)2溶液为凝胶改良剂、超细Fe2O3为引晶剂、采用溶胶-凝胶工艺制备了超微晶陶瓷氧化铝磨料。对磨料的密度、硬度、韧性及磨削性能进行了测定。用正交实验考察了pH值、引晶剂、凝胶改良剂量等因素对磨料性能的影响。结果表明:各因素的影响顺序为引晶剂Fe2O3%量>酸度pH值>凝胶剂量。引晶剂Fe2O3%量不同,制得的磨料各项性能差别较大,添加量约为0.50%时、制得的磨料具有较佳的性能,磨料的密度为3.91g/mL、显微硬度为236MPa、磨削性能为传统刚玉的3.5倍。磨料性能可以和进口SG磨料相媲美。SEM电镜结果表明:该种磨料的晶粒度比较均匀,颗粒度较小,颗粒间不存在裂痕,样品的粒度在200-400nm。     

95Al2O3陶瓷件的活性钎焊

对活性封接在真空器件制造中的应用进行了分析探讨,针对自制Ag-26.5Cu-4.5Ti(质量分数,%)钎料测试了钎料熔化温度范围以及对95Al2O3陶瓷的润湿铺展特性,制备了95Al2O3 /Ag-26.5Cu-4.5Ti搭接接头,并分析了接头组织形貌。针对真空器件封接需求,重点对95 Al2O3陶瓷进行了活性钎焊封接试验,测试钎焊强度及漏气率。     

Fe3Al纳米粒子增强Al2O3陶瓷的制备及性能

用热压烧结法制备了纳米Fe3 Al粒子增强Al2 O3 基复合材料。研究了 14 5 0～ 16 0 0℃不同烧结温度下纳米Fe3 Al的加入量与材料的致密度、力学性能及显微结构的关系。结果表明 :纳米Fe3 Al的加入可使Al2 O3 晶粒的生长受到抑制 ,使复合材料的烧结温度提高。Fe3 Al/Al2 O3 纳米复合材料有良好的力学性能 ,其抗弯强度最高可达832MPa ,断裂韧性最高可达 7.96MPa·m1/ 2 。