ZrO2—SiO2—Al2O3系复相陶瓷制备及其耐磨性试验研究

利用等离子分解锆英石（PDZ）和锆英粉与Al2O3反应烧结制务了ZrO2-SiO2-Al2O3系复相陶瓷。利用XRD,SEM,反应显微镜,显微硬度计等测试手段,对烧成试样的物相相成,显微结构,显微硬度,气孔状况及耐磨性进行了测试分析与讨论,研究结果表明：含镁助剂的加入促进了反应烧结;由PDZ制备的试样的性能优于锆英粉原料的试样,较佳的原料配比为No.4即Al2O3:PDZ=3:1,其耐磨性优于氧化铝质研磨体;适宜的烧成温度范围是1580℃－1600℃。     

ZrO_2-SiO_2-Al_2O_3系复相陶瓷制备及其耐磨性试验研究

利用等离子分解锆英石(PDZ)和锆英粉与Al_2O_3反应烧结制务了ZrO_2－SiO_2－Al_2O_3系复相陶瓷。利用XRD、SEM、反应显微镜、显微硬度计等测试手段,对烧成试样的物相相成、显微结构、显微硬度、气孔状况及耐磨性进行了测试分析与讨论。研究结果表明：含镁助剂的加入促进了反应烧结;由PDZ制备的试样的性能优于锆英粉原料的试样;较佳的原料配比为No.4即Al_2O_3:PDZ=3:1,其耐磨性优于氧化铝质研磨体;适宜的烧成温度范围是1580℃～1600℃。     

β-sialon/Al2O3/CaO系材料烧结性能及反应过程研究

以β-sialon、活性氧化铝微粉和纯铝酸钙水泥为原料，研究了焦炭保护情况下，在1500～1650℃温度范围内，sialon／Al2O3／CaO体系材料的烧结性能和物相变化，借助SEM和XRD等手段对材料的显微结构和反应过程进行了观察和分析。结果表明：该体系材料烧结性能与试样组成和烧成温度有关。温度升高，试样体积密度增加，显气孔率降低，当温度升高至1650℃，试样烧结性能反而下降。试样在烧成过程中存在质量变化，1500℃下烧成试样均表现为质量增加，而1600℃以上试样表现为质量损失。从热力学分析推测烧成过程中试样内部存在复杂化学反应，在温度低于1500℃时sialon与CO反应使碳析出，导致试样质量增加；而温度进一步升高，sialon和Al2O3将被还原形成Al7O9N(s)和SiC(s)，导致试样质量损失。X射线衍射分析显示：烧成材料中除含有刚玉、sialon相外，随烧成温度增加还出现物相变化：1500℃形成钙黄长石相；1600℃时钙黄长石相消失，出现了Ca-α-sialon和SiC；温度升至1650℃，出现γ-AION。     

Ca-Ba-Mg-Al-B-Si-O玻璃/Al2O3系LED基板材料的工艺优化与性能研究

实验以玻璃与Al2O3为主要原料流延成型生瓷带,通过优化试样的压制工艺,800～950℃范围内烧结得到Ca-Ba-Mg-Al-B-Si-O玻璃/Al2O3材料。研究结果表明,随着Ca-Ba-Mg-Al-B-Si-O玻璃/Al2O3生坯压制压力变大或保压时间增加,玻璃/Al2O3材料的生坯及烧结试样的密度增加,烧成收缩率减小。850℃烧成试样结构致密,钙离子、铝离子、硅离子与氧离子在高温下聚集,并发生了物理化学反应,生成钙长石晶体,进一步促进了烧成试样的致密化。Ca-Ba-Mg-Al-B-Si-O玻璃/Al2O3材料在压力20 MPa,保压时间10 min下成型生坯性能良好,烧结体物理性能优良,适合用于LED基板材料。     

β-sialon/Al2O3/SiO2系材料烧结性能及反应过程研究

以β-sialon粉、活性氧化铝微粉和氧化硅微粉和氧化硅微为原料，研究了在焦碳保护下，β-sialon/Al2O3/SiO2体系材料经1500，1600，1650℃烧成时，该体系材料的烧结性能和物相变化，同时借助于SEM，EDX和XRD等手段对材料的显微结构和反应过程进行了观察和分析。结果表明，随着温度升高，β-sialon/Al2O3/SiO2体系材料的体积密度下降，显气孔率增加，同时试样烧成前后的质量损失大大增加，尤其是经1650℃烧成的试样，显气孔率在50?陨希柿克鹗Т笥?0?RD物相分析显示1500℃时，产物中生成X相（Si12Al18O39N8)和SiC，高于1650℃生成r-AlON和SiC相，与热力学计算结果一致。同时高温下大量低价态的氧化铝如Al(g)及SiO(g)气相物质逸出试样表面，可能是导致试样质量损失，结构松散，显气孔率增加的主要原因。切开经高温烧成的试样，其截面由中心致密区，过渡区和边缘的松攻区3部分组成，含氮物相的形状由中心部位发育良好的柱状，演变成过渡区的针状或须状，直至松散区消失。这种松散区所占面积取决于试样的烧成温度和组成。     

Al-Al2 O3-MgO混合粉的氮化反应烧结行为

以金属铝、镁铝尖晶石和氧化铝及氧化镁细粉为原料,研究了Al-Al2O3-MgO体系混合粉料的氮化反应烧结行为.结果表明Al/Al2O3、原料的种类、烧成温度等对试样的烧结性能有很大的影响.通过选择合适的原料及配比,可得到比较适宜于直接制备MgAlON结合复合材料的基质料.     

无压烧结制备Al2O3/SiC纳米复合陶瓷

用沉淀法包裹微米级SiC颗粒，通过常压、埋烧制备Al2O3／SiC纳米复合陶瓷。通过XRD、TG和SEM等分析了煅烧和烧结过程中相组成的变化、烧成收缩和显微结构。结果表明：利用SiC粉埋烧及碳粉制造还原气氛，含8wt％SiC(平均粒径为5mm)的复合粉末经800℃煅烧、成型，试样于1550℃，2h烧结，可制备Al2O3／SiC纳米复合陶瓷，其相对体积密度达95．2％，在烧结过程中由SiC氧化形成的无定形SiO2及与基质氧化铝反应形成的莫来石前躯体可大大促进烧结。     

Al2TiO5-SiO2-Al2O3复合材料的研究

以Al2TiO5微细粉、SiO2-Al2O3微细粉为原料,外加6%(质量分数,下同)PVA结合剂,100 MPa压力成型,1400 ℃保温1 h烧成,制备出低热膨胀系数,抗热震性能优于SiO2-Al2O3材料的Al2TiO5-SiO2-Al2O3复合材料.对复合材料的性能测定分析,研究不同的Al2TiO5含量、烧结温度等对Al2TiO5-SiO2-Al2O3复合材料性能的影响,获得了制备性能优良的Al2TiO5-SiO2-Al2O3复合材料的最佳工艺参数.     

Ti粉加入量对Al_2O_3-C材料强度与抗氧化性的影响

以白刚玉、鳞片石墨为主要原料,分别外加质量分数为0、2.5%、5%、7.5%、10%的Ti粉,经等静压成型,在流动氮气中于1350℃4 h烧成,制备了含Ti的Al2O3-C试样,测试了试样的常温耐压强度、常温抗折强度和1 400℃2 h下的抗氧化性,用XRD分析了试样及其脱碳层的相组成,并用SEM观察试样脱碳层的显微形貌。结果表明:1)在流动氮气中烧成,Ti粉易于转化为TiC1-xNx(其中0≤x≤1),增强了物相间的结合力,且TiC1-xNx钉扎在基体中,增大了基体间滑移的摩擦力,提高了Al2O3-C试样的强度,外加Ti粉质量分数为5%时最佳;2)加Ti粉的Al2O3-C试样在空气中氧化时,TiC1-xNx氧化后的体积膨胀弥补了石墨被氧化后留下的空隙,阻止了外部O2的扩散,同时在高温的作用下,脱碳层氧化物间形成的钛酸铝和莫来石能胶结基体形成致密层,有效地减缓了内层非氧化物的氧化,提高了Al2O3-C试样的抗氧化性能。     

铅硼硅酸盐玻璃中Al_2O_3含量对复相玻璃陶瓷性能的影响

以低软化点的铅硼硅酸盐玻璃和Al2O3粉末为原料,制备Al2O3/玻璃低温共烧复合玻璃陶瓷材料。考察烧结温度和添加不同质量分数的Al2O3对复合玻璃陶瓷烧结机制和微波介电性能的影响,并探讨了作用机制。结果表明:Al2O3掺入PbO-B2O3-SiO2玻璃中改善了与Al2O3陶瓷的界面润湿,对烧结有一定的促进作用。在添加质量分数为4%Al2O3的复相玻璃陶瓷、烧成温度为850℃时性能最好,其密度为3.1 g/cm3,介电常数为8.46,介电损耗为0.001 1。     

Wear behavior and microstructure of alumina-mullite-zirconia composites prepared by a novel method: Coating of zircon powder by aluminum alkoxide

The formation of the mullite phase is the main challenge in the preparation of alumina-mullite-zirconia (AMZ) composites. To overcome this limitation, a novel method based on the coating of zircon powder with aluminum alkoxide was proposed in this study. Reaction sintering of alumina and coated zircon was carried out at 1630 °C for 3 h. The microstructural, physical, mechanical, and tribological properties of samples were compared with the conventional AMZ composites prepared by common mixing of alumina and zircon. The microstructural analysis indicated the higher alumina phase of the sample prepared with the conventional method. On contrary, the samples prepared with the proposed method included higher percentages of mullite phase. In terms of mechanical properties, the conventional AMZ samples performed better. However, due to the beneficial effect of the mullite phase in tribological applications, the samples prepared with this new method show superior wear resistance. Especially, the samples prepared from 30 wt% aluminum alkoxide exhibited the best wear resistance. The delamination and adhesive wear mechanisms govern the wear process.     

Study on microstructure and abrasive wear behavior of sintered Al matrix composites

Abrasive wear behavior of ZrSiO₄ reinforced aluminum metal matrix composite has been investigated in the present research. In general, composites offer superior wear resistance as compared to the alloy irrespective of applied load and zircon particles volume fraction. During sliding wear of the composite, a layer is formed over the specimen surface, which strongly dictates the wear behavior of the materials. It is believed that these layers are formed due to formation of wear debris, transfer of materials from the counter surfaces and mixing of these materials on the contact surfaces. The wear sliding test disclosed that the weight loss of the composites decreases with increasing volume fraction of zircon particulates. The composite samples were examined by X-ray diffraction technique and scanning electron microscopy which confirm the uniform distribution of zircon particles through the matrix. The hardness of the composite was affected significantly by the amount of porosity and reinforcement phase as two dominant factors.     

添加Nd_2O_3对高铝瓷的耐磨性及结构影响

实验以工业氧化铝为主要原料,对Al2O3含量为98%的氧化铝陶瓷进行研究。实验主要过程为:在Ca-MgAl-Si-O体系中添加不同量的稀土氧化物Nd2O3,并在不同温度下烧结,利用X射线粉末衍射(XRD)以及场发射扫描电镜(SEM)对所得复合陶瓷的显微结构和物相组成进行分析,并且测试其吸水率和磨损率。结果表明:Nd2O3掺入使陶瓷晶粒均匀化,并且少量Nd3+可以促进片状晶体的形成,从而使得磨损率获得大幅度的降低。     

Sliding Wear of Alumina/Silicon Carbide Nanocomposites

The wear resistance of four Al₂O₃/SiC nanocomposites that contained SiC particles of varying average size (40, 200, and 800 nm) was studied under dry sliding conditions and compared with the results obtained in unreinforced alumina. The wear rate of the alumina and the nanocomposites of equivalent grain size increased as the contact load increased; however, the nanocomposite wear resistance at high contact loads was better than that of the alumina by a factor of 3–5. The wear resistance of the nanocomposites of submicrometer grain size was fairly independent of the contact load, and their wear resistance at high contact loads was up to two orders of magnitude better than that of the alumina. The mechanisms responsible for these behaviors were discussed in terms of the microscopic wear mechanisms that were observed on the worn surfaces.     

Dry reciprocating sliding wear behaviour of alumina-silicon carbide nanocomposite fabricated by ceramic injection molding

The wear resistance of Al₂O₃ composite with 6 vol.% of SiC nanoparticles fabricated by thermoplastic forming technology and natural sintering was studied under reciprocating dry sliding conditions and compared with the results obtained in unreinforced alumina with similar grain size obtained by hot pressing. The nanocomposite wear resistance at contact loads of 20 N corresponding to initial Hertzian contact pressures of 1.8 GPa, was found to be superior to that of the alumina by a factor of 6.     

Submicrometer Transparent Alumina by Sinter Forging Seeded γ-Al2O3 Powders

Seeding boehmite with α-Al₂O₂, followed by calcination at 600°C, results in an agglomerated alumina powder (<53 μm) that can be sinter forged to full density at 1250°C. Compressive strains as high as ɛ_x=−0.9, and radial flow (ɛ_x= 1.0) during sinter forging remove large, interagglomerate pores. The fully dense alumina has a grain size of 0.4 pm and is visually transparent. It is proposed that deformation of dense agglomerates is the primary mecha- nism responsible for large pore elimination and compact densification. The sinter forging of sol-gel-derived alumina powders offers a new technology to prepare highly transparent, optical ceramics at lower temperatures than conventional routes.     

The wear resistance of Ni alumina and NiAl2O4 alumina nanocomposites

The influence of metallic Ni or NiAl₂O₄ as a reinforcing particle on grain growth and wear resistance in alumina matrix composites was evaluated. Alumina composites with various Ni or NiAl₂O₄ concentrations were prepared by multiple-infiltrations of Ni-nitrate into bisque-fired (necked) alumina green bodies followed by heat treatment and sintering at 1600 °C for 2 h. Sintering in a reducing environment resulted in composites with metallic Ni nanoparticles, while NiAl₂O₄ alumina composites were formed when sintering in air. The addition of Ni or NiAl₂O₄ resulted in a reduction in alumina grain size after sintering. The material response to abrasive wear was estimated by measuring the time to section samples of a defined area using a diamond wafering saw and was compared to the wear resistance of undoped alumina. In both cases, reinforcing alumina with Ni or NiAl₂O₄ particles resulted in a significant increase in wear resistance, correlated to the reduced grain size.     

Alumina/Zirconia Micro/Nanocomposites: A New Material for Biomedical Applications With Superior Sliding Wear Resistance

In the present investigation, the sliding wear behavior is described for Al₂O₃/ZrO₂ micro/nanocomposites and monolithic alumina of similar grain size under defined conditions of a constant sliding speed and different loads (20–150 N). Nano ZrO₂ particles (1.7 vol%) were observed uniformly distributing throughout the composites, and most of them were located within the matrix alumina grains. The wear rate of the alumina and the micro/nanocomposites increased as the contact load increased and a clear transition in friction and wear behavior was observed in both materials. However, the nanocomposite wear resistance at low contact loads was one order of magnitude higher than that of the alumina. In the severe regime, no difference was observed among the materials. The low wear rate (10⁻⁷ mm³·(N·m)⁻¹) along with low pullout indicates higher wear resistance of micro/nanocomposites in the mild regime compared with monolithic alumina. Based on the morphological observation of worn surfaces by scanning electron microscope and on residual stress analysis performed by neutron diffraction, some wear mechanisms of Al₂O₃–ZrO₂ micro/nanocomposites are proposed. The high wear resistance of the nanocomposites is discussed in terms of fracture resistance properties and residual stress. Improvements in mechanical and tribological properties of these composites make them promising candidates for biomedical applications.     

Corrosion- and wear-resistant properties of Ni–Al<Subscript>2</Subscript>O<Subscript>3</Subscript> composite coatings containing various forms of alumina

This article describes the effect of the addition of different phases of alumina particles on the properties of electrodeposited Ni–Al₂O₃ composite coatings. The corrosion- and wear-resistant properties of Ni–Al₂O₃ composite coatings electrodeposited from a nickel sulfamate bath containing (i) alpha-alumina particles (Ni–Al₂O₃-1), (ii) gamma-alumina particles (Ni–Al₂O₃-2), and (iii) mixture of alpha, gamma, and delta alumina particles (Ni–Al₂O₃-3) have been studied. The potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) studies showed superior corrosion resistance of Ni–Al₂O₃-2 composite coatings compared with other two coatings. The SEM images and EDAX spectra also corroborated well with the observed corrosion results. The pin-on-disk wear studies showed improved wear resistance of Ni–Al₂O₃-1 composite coating containing alpha alumina compared with other two coatings. The transfer of material from the pin onto the disk was evident from the optical microscopy images of the wear tracks and Raman spectra of the wear track. This study shows that the addition of pure gamma-alumina particles enhances the corrosion resistance, and that pure alpha-alumina particles enhance the wear resistance of Ni composite coatings to a greater extent.     

纳米Al_2O_3粉末改善环氧树脂耐磨性的研究

进行了利用纳米氧化铝 (α -Al2 O3 和γ -Al2 O3 )改善环氧树脂耐磨性能的研究。利用超声分散法将纳米氧化铝粉末加入环氧树脂之中 ,利用磨损失重法评价了环氧树脂复合材料的耐磨性能 ,通过扫描电镜观察了纳米粉末在环氧树脂中的分散情况 ,尝试解释了纳米氧化铝提高环氧树脂耐磨性能的机理 ,并确定了较优的纳米氧化铝添加量。试验表明 ,填充纳米氧化铝粉末可以提高环氧树脂的耐磨性能。较优的配方为EP (E - 5 1) 1份 ,PA6 5 10 7份 ,KH - 5 5 0 0 0 4份 ,30～ 6 0nmγ -Al2 O3 0 1份。