热浸铝钢等离子体电解氧化陶瓷层的微观力学特性

采用纳米压入方法表征了热浸镀铝钢表面由Al2O3层、Al层和FeAl层组成的复合涂层的纳米硬度、弹性模量及断裂韧性等微观力学性能,采用扫描电镜(SEM)观察了纳米压痕形貌,并分析了孔洞对陶瓷层的纳米压入行为和压痕裂纹扩展的影响.结果表明:等离子体电解氧化(PEO)陶瓷层中包含许多微米和亚微米尺度的细小孔洞,陶瓷层弹性模量约为226.4 Gpa,纳米硬度约为19.6 Gpa.当纳米压入深度为250 nm时,所测得陶瓷层的力学参数分散性较大.与FeAl层比较,PEO陶瓷层具有较高的裂纹扩展阻力. FeAl层纳米压痕顶端产生了沿直线扩展的径向裂纹;而陶瓷层纳米压痕中除径向裂纹外出现了侧边裂纹.     

纳米Cr2O3微粒对2024-T4微弧氧化膜结构及耐磨性能的影响

摘 要: 在含有不同浓度纳米Cr2O3微粒的硅酸盐体系电解液中对2024-T4铝合金进行微弧氧化处理,使用SEM观察陶瓷膜的表面形貌和截面形貌,使用EDS能谱仪分析膜层中各主要成分沿截面方向的分布,使用XRD分析陶瓷膜的相结构,使用纳米压痕硬度计测量陶瓷膜的硬度,使用粗糙度仪测量陶瓷膜的表面粗糙度,使用摩擦磨损试验机测量陶瓷膜的摩擦系数,使用激光共聚焦显微镜测量磨痕体积,评估磨损率,使用SEM观察磨痕形貌,结果表明：在电解液中加入纳米Cr2O3微粒后,制备的陶瓷膜中出现了Cr2O3相,电解液中纳米Cr2O3微粒浓度达到2.4g/L时,陶瓷膜的硬度最高,摩擦系数最小,磨损率最低,耐磨性最好。     

Crack healing and strength recovery of Al2O3/TiC/TiB2 ceramic tool materials

Because ceramic tool materials are sensitive to defects such as microcracks, this paper develops ceramic tool materials with crack healing function to solve this problem. In this paper, Al₂O₃/TiC/TiB₂ ceramic tool materials were prepared by vacuum hot pressing sintering technology. Cracks of different lengths are prefabricated on the surface of the material through Vickers hardness tester. The crack healing of the material was studied by high temperature air heat treatment. According to the recovery of material strength after heat treatment and the change of microstructure, the crack healing effect of the material was judged. The effects of different heat treatment temperature, heat treatment time and crack length on the healing behavior of ceramic materials were mainly studied. Research shows that the surface crack of the material is completely filled and healed by oxidation products. The flexural strength of the specimen with pre-cracked surface is only 24.50% of that of the smooth specimen. After heat treatment at 700 °C for 60 min, the strength of the cracked specimen returns to 91.35% of that of the smooth specimen. The maximum effective crack length for crack healing of this ceramic material is 500 μm. Through micro-morphology and elemental analysis, it is found that the main mechanism of surface crack healing is the filling and healing of cracks by liquid phase oxidation products of titanium diboride, namely boron trioxide and titanium dioxide, thus restoring the flexural strength of the material.     

Y2O3-MgO纳米复相红外透明陶瓷制备及其性能研究

以商用Y2O3、MgO纳米粉体为原料,通过球磨混合方法制备了不同Y2O3/MgO配比的Y2O3-MgO纳米复合粉体,使用X射线衍射、扫描电镜、能量色散谱等表征手段对制备粉体的晶体结构、形貌、成分以及均匀性进行了表征。然后采用热压烧结方法制备Y2O3-MgO复相红外透明陶瓷,使用红外光谱仪、维氏硬度计等测试设备对复相透明陶瓷的光学和力学性能进行了分析。重点研究了粉体配比、热压温度、保温和保压时间等关键制备参数对Y2O3-MgO复相红外透明陶瓷晶粒尺度、致密化程度、光学及力学性能的影响。并通过调控粉体制备工艺和热压烧结工艺,制备出了红外透过率达到~80%的Y2O3-MgO复相红外透明陶瓷。同时在Y2O3:Mg0=1:1时,该复相陶瓷的硬度达到了12.3 GPa。     

反应等离子喷涂AlNbO4-Al2O3-NbOx复合涂层的研究

目的研究等离子喷涂Al-Nb_2O_5铝热体系制备的AlNbO_4-Al_2O_3-NbO_x复合涂层的组织、力学性能和摩擦磨损性能。方法以Nb_2O_5粉和Al粉为原料,通过喷雾造粒制备复合粉,采用等离子喷涂技术喷涂Al-Nb_2O_5复合粉体,利用复合粉的自反应制备出含有AlNbO_4、Al_2O_3和NbO_x的复合陶瓷涂层。利用扫描电镜、EDS和XRD检测和分析复合涂层的组织和物相。用显微硬度计测定复合涂层的硬度,并用硬度压痕法测量裂纹扩展能(Gc)。用销盘式磨损试验机测定涂层在无润滑条件下的摩擦磨损性能。结果 XRD分析可知,复合涂层由AlNbO_4、Al_2O_3和NbO_x相组成,SEM显示涂层为交替分布的层片状组织。在28~32 k W功率范围内,随着喷涂功率的升高,涂层的硬度增加,喷涂功率为32 k W时,涂层硬度最高,为912HV0.1。随着喷涂功率的升高,涂层的裂纹扩展能先升高后降低,喷涂功率为30 k W时,涂层的裂纹扩展能最大,为14.14J/m2。摩擦系数随功率的升高先降低后保持不变,28 k W时,涂层的摩擦系数为0.7~0.8,30 k W和32 k W时,涂层的摩擦系数为0.5~0.6。磨损量随喷涂功率的增加先降低后升高,喷涂功率为30 k W时,涂层的磨损量最小。磨损后的试样进行SEM检测发现有明显的犁沟、凹槽和剥落。结论涂层具有由AlNbO_4、Al_2O_3和NbO_x相组成的交替分布的多相层片状组织。喷涂功率为30 k W时,复合涂层的性能最好。复合涂层的主要磨损机制为磨粒磨损和疲劳磨损。     

仿生结构复合陶瓷刀具材料力学性能及显微结构

针对不同烧结条件及TiC/WC组分比,采用热压烧结工艺制备出三层仿生结构复合陶瓷刀具材料。测试了仿生结构复合陶瓷材料力学性能,并对材料断口形貌和裂纹扩展进行了观察分析。结果表明：仿生结构复合陶瓷刀具材料抗弯强度达870 MPa,维氏硬度达21.83 GPa,断裂韧性达7.56 MPa?m_1/2,比SG4均质陶瓷刀具材料性能有所提高。断口形貌显示仿生结构复合陶瓷刀具材料较SG4均质刀具材料晶粒细密,晶粒尺寸呈现多尺度特征。材料断裂模式为穿晶断裂和沿晶断裂混合型。仿生结构复合陶瓷材料表面裂纹扩展呈现偏转和分叉。裂纹穿过材料界面扩展时有明显偏转现象。     

TiB_2和SiC_w对Al_2O_3陶瓷材料力学性能及微观结构的影响

以TiB2颗粒和SiC晶须对Al2O3陶瓷进行增韧补强,采用热压法同时了制备了Al2O3,Al2O3／TiB2和Al2O3／TiB2／SiCw三种陶瓷材料,研究了TiB2颗粒和SiC晶须对Al2O3陶瓷材料的力学性能和微观结构的影响。结果表明;因TiB2的加入可明显改善Al2O3。陶瓷材料的强度、硬度和韧性;而TiB2颗粒和SiC晶项协同对Al2O3进行增韧补强可使其断裂韧性显著提高。Al2O3／TiB2陶瓷材料的主要增韧机理有;TiB2粒子的针扎作用和使裂纹产生偏转;而Al2O3／TiB2／SiCw陶瓷材料的主要增韧机理有：晶须拔出、裂纹桥接和裂纹偏转。     

Al2O3对等离子喷涂Cr2O3/TiO2/Al2O3/SiO2复合陶瓷涂层性能影响研究

目的研究Al_2O_3添加量对Cr_2O_3/TiO_2/Al_2O_3/SiO_2四元复合陶瓷涂层性能的影响。方法采用等离子喷涂技术在油气管道X80管线钢基体表面制备出具有不同Al_2O_3含量的四元复合陶瓷涂层。另外,为探究基体温度对涂层性能的影响,所有涂层均在等离子喷枪预热及室温的两种基体上制备。所制涂层的气孔率、硬度、结合力及电化学腐蚀性能分别采用煮沸称重法、维氏硬度计、划痕仪、电化学工作站进行检测,并用X射线衍射仪(XRD)、扫描电镜(SEM)分析不同Al_2O_3含量涂层的物相组成和形貌特征,研究Al_2O_3含量对涂层各性能的影响。结果随着Al_2O_3含量的增加,Cr_2O_3/TiO_2/Al_2O_3/SiO_2四元复合陶瓷涂层的气孔率呈现先降低后增加的趋势,相对应的四元复合陶瓷涂层的结合力、维氏硬度则先增加后降低。当Al_2O_3质量分数为60%时,四元复合陶瓷涂层的性能最优,气孔率为3.6%,硬度为824.6HV,结合力为53.8N。电化学腐蚀测试表明,Al_2O_3能增强涂层的耐腐蚀性能,Al_2O_3质量分数为60%时,涂层自腐蚀电位最高,为-0.28 V。另外,在基体预热和不预热条件下,所制涂层性能随Al_2O_3含量的变化一致,但是基体预热比不预热更有利于涂层性能的提高。结论 Al_2O_3的添加不仅能够有效降低涂层Cr含量,还能显著提升四元复合陶瓷涂层的各项性能,特别是耐腐蚀性。此外,等离子喷涂前对基体进行预热,有利于涂层性能提高。     

SHS制备纳米/微米结构抗弹陶瓷可行性研究

针对用于现代装甲防护的高性能抗弹陶瓷，以SHS冶金技术，通过材料原位合成手段并在大过冷条件下熔体发生共生共晶反应，快速一次性制备出自燃自组装、具有1-3复合晶内型结构的纳米／微米结构Al2O3-ZrO2共晶复相陶瓷。Vickers压痕试验发现该陶瓷具有较高的断裂韧性并表现出较强的塑变行为，SEM观察发现该复相陶瓷的裂纹扩展路径主要受纳米／微米结构(Al2O3-ZrO2)共晶结构所控制，影响该陶瓷韧化行为的主要因素在于以“内晶型”纳米相所构成的独特的增韧机制。试验预示着采用SHS冶金技术，通过控制Al2O3/ZrO2复相陶瓷成分和凝固行为(如采用离心冷却控制技术)，可以制备出用于现代装甲防护的高性能、低成本、高可靠性新型抗弹复相陶瓷面板。     

Interface of 3D Micro-cellular Structural AlMnCe/Al_2O_3 Composite

The AlMnCe/Al2O3 metal/ceramic composite with 3D micro-cellular structure is prepared by spark plasma sintering (SPS) at 520 ℃. It consists of consecutive nano-Al2O3 sintering body phase and AlMnCe alloy discrete phase. The microstructure of sample, characteristic of the micro-cellular structure and microstructure of the interface are investigated via scanning electron microscope (SEM) and transmission electron microscope (TEM) method. The results indicate that two kinds of interfaces are formed in the sample during SPS process, one is the micro-nano type metal/ceramic interface between the metal cellular body and the nano-ceramic cellular wall, the other is the nano-nano type ceramic/ceramic interface in the nano-ceramic cellular wall. The fusion transition area with a width 200-300 nm at interface of the AlMnCe alloy and nano-Al2O3 sintering body is formed. The AlMnCe alloy has a sufficient immersional wetting for the Al2O3 cellular wall. The bonding of interface between the nano-Al2O3 sintering body and the AlMnCe alloy particle is powerful, and new phase and crack is not found.