Fe3Al基复合材料的制备及其摩擦磨损行为

用球磨机械合金化工艺制备Fe3Al粉末，采用粉末冶金工艺，选择不同的烧结温度和烧结压力，获得了Fe3Al基复合材料。对材料的物理力学性能、摩擦磨损性能和微观结构进行分析测试，借助磨损表面扫描图像，分析了该材料的磨损形式，探讨了其磨损机理。结果表明：在烧结温度为1050℃，烧结压力为10～15MPa的工艺条件下制得的Fe3Al基复合材料有较好的摩擦磨损性能。其摩擦机理为：疲劳磨损和磨粒磨损为主，兼有磨粒和粘着磨损混合形式。     

凝胶注模制备多孔Ni-Ti合金的研究

多孔Ni-Ti合金由于其优异的形状记忆性能而广泛应用于医用植入材料领域。本文以TiH2粉及雾化Ni粉为原料,采用凝胶注模成型技术,制备出Ni-Ti凝胶生坯,通过后续真空干燥、脱脂以及烧结工艺成功制备出性能优异的医用植入多孔Ni-Ti合金。运用XRD、SEM对多孔Ni-Ti合金进行了成分及微观结构表征,分析了不同烧结温度对于多孔Ni-Ti合金孔隙率、机械性能、组织成分及微观形貌的影响。结果表明,随着烧结温度的增加,孔隙率降低,抗压强度和杨氏模量增加。对固相体积分数为45vol. %的生坯在1050 ℃条件下高真空烧结保温2h,制备出孔隙率为42.65%,抗压强度为202.65 MPa,杨氏模量为17.14 GPa,主相为NiTi相的多孔Ni-Ti合金,基本满足人体骨性能需要。     

冶金硅渣烧结多孔微晶玻璃的结构及性能

以冶金硅渣为主要原料,采用水淬粉体直接烧结工艺,制备多孔微晶玻璃。利用XRD、DTA/TG、SEM以及图像分析等技术,研究烧结工艺对多孔微晶玻璃气孔孔径、表观密度、晶相组成以及抗压强度的影响。结果表明:多孔微晶玻璃的气孔孔径随烧结温度升高以及烧结时间延长而增大,随升温速率的增大先增大后减小;表观密度随烧结时间延长逐渐增大,随烧结温度升高和升温速率增大呈现出先减小后增大的趋势;抗压强度随烧结温度升高先缓慢增大后急剧降低。多孔微晶玻璃最佳烧结工艺是以30℃/min的升温速率加热到800℃烧结30 min,此时多孔微晶玻璃的平均孔径为1.2 mm,表观密度为0.81 g/cm~3,抗压强度为4.6 MPa。     

Fe3Al多孔材料预氧化性能研究

以Cr改性的Fe3Al预合金粉末为原料,采用粉末冶金方法制备Fe3Al多孔材料,研究氧化温度、时间、降温速度对Fe3Al多孔材料氧化膜性能的影响。结果表明:Fe3Al多孔材料的氧化增重随温度的升高而增大,氧化动力学遵循四次方规律,在800℃的大气中氧化9h,氧化膜已完全将烧结颈覆盖,晶粒细小;随着温度的升高和时间的延长,晶粒变得粗大;900℃氧化5h,膜层已出现裂纹;而降温速度对氧化增重的影响不大,也没有出现由于热膨胀不匹配而产生的裂纹。     

烧结温度对Ni16Cr9Al多孔材料性能的影响

以粒度小于25 μm的Ni16Cr9Al预合金粉末为原料,采用模压成形、真空烧结的方法制备了Ni16Cr9Al多孔材料,研究了烧结温度对Ni16Cr9Al多孔材料性能的影响。结果表明：Ni16Cr9Al粉末压坯在烧结过程中由于烧结颈的形成、长大,体积发生收缩,随着温度的升高,烧结体的孔隙度和孔径减小,强度提高,1130 ℃具有良好的三维孔隙结构,高于1150 ℃,孔隙减少,材料逐渐致密     

规则多孔钼的制备及其吸能特性研究

采用尿素作造孔剂,利用"层铺法"和真空烧结技术制备了孔隙率及孔隙结构可控的多孔钼材料。利用金相显微镜和扫描电镜研究了尿素含量、压制压力和烧结温度对多孔钼孔隙率和微观结构的影响。结果表明,"层铺法"能有效保证多孔钼孔隙的均匀分布及连通性;生坯致密度随压制压力的增大而增大;在1800℃烧结能获得良好的钼粉结合。在加载过程中,多孔钼主要通过孔隙壁的断裂、坍塌及孔隙壁碎片的摩擦来吸收能量。     

多孔NiAl金属间化合物的造孔机理

以Ni、Al元素粉末为原料,采用反应烧结工艺制备多孔NiAl金属间化合物材料,表征各烧结温度所对应的孔结构,研究NiAl烧结体的造孔机理。结果表明:在多孔NiAl金属间化合物材料的制备过程中,当温度在1 100℃以下,随着烧结温度的升高,NiAl烧结体中的孔隙度和最大孔径呈现增大的趋势;经1 100℃烧结之后,多孔NiAl的孔隙度为53%,最大孔径为55μm;造孔机理为Al熔点附近的Ni、Al之间的剧烈扩散造孔形成大量的开孔隙度,以及高温烧结阶段的Ni与中间相的扩散形成的多孔NiAl材料骨架中的孔洞。     

粉末冶金制备50%SiC_p/Al复合材料的结构及性能

采用球磨加常压烧结的粉末冶金工艺制备50%SiC_p/6061Al(体积分数)复合材料,研究了烧结温度对该高体积分数SiC_p/Al复合材料结构与性能的影响。结果表明:球磨有利于形成成分均匀的50%SiC_p6061Al复合粉体;随着烧结温度的升高,50%SiC_p/6061Al复合材料的致密度及抗弯强度先增后减。710℃烧结的复合材料性能最佳,致密度达到97%,抗弯强度大于400 MPa。该复合材料中SiC_p呈解理断裂,而Al合金基体呈韧性撕裂的断裂特征。750℃烧结的50%SiC_p/6061Al复合材料中,SiC_p/Al界面反应加剧,生成较多的Al4C3相,导致复合材料结构劣化,性能降低。     

烧结温度对Al3Zr/2024Al多孔复合材料的组织与压缩性能的影响

以NaCl为造孔剂,2024Al和Zr粉末为基体,通过造孔剂法制备了Al₃Zr/2024Al多孔复合材料,研究了不同烧结温度对复合材料组织与压缩性能的影响。结果表明:复合材料的孔隙率几乎不受烧结温度影响;烧结温度的升高可促进Al₃Zr在孔壁内生成、扩散和团聚长大;压缩试验结果表明Al₃Zr可明显提高复合材料的压缩性能,压缩强度随烧结温度的升高呈现先增大后减小的趋势,在650℃时屈服强度可达57.12 MPa,平台应力可达56.8 MPa,此时Al₃Zr/2024Al多孔复合材料具有最佳的压缩、吸能性能。     

新型超轻TiAl多孔材料的制备及其力学性能

基于化学反应造孔和物理占位造孔的联合作用,发展了一种新型Ti Al金属间化合物多孔材料的制备工艺,具体可用均混、压制、脱溶、烧结4个阶段来描述。该工艺实现了毫/微米双孔结构Ti Al多孔材料的制备,其中微米孔由Kirkendall效应产生,毫米孔由物理占位造孔颗粒实现。材料具有完全的通孔结构,孔洞分布均匀,且孔隙率、孔径、孔型、孔结构可控,最高孔隙率可达90%。准静态压缩力学性能测试表明,Ti Al多孔材料属于脆性多孔材料,具有典型的脆性破坏断裂机制,其屈服强度与相对密度的关系可通过Gibson-Ashby正六面体单胞模型来解释。     

Microstructure and Tensile Properties of Nanostructured and Ultrafine Grained FeMoB Alloys Produced by Spark Plasma Sintering of Mechanically Alloyed Powders

Boron alloyed Fe-1.5%Mo alloys (B from 0.42 to 1.66%) were produced starting from a prealloyed ferrous powder and an elemental boron powder, by mechanical alloying and spark plasma sintering. Near full density samples were obtained (density >99%) with a nano- and ultrafine grained structure, consisting in a ferritic matrix with a fine dispersion of Fe and Mo borides. High boron content and a low sintering temperature are favorable to minimize grain growth on sintering. On increasing the boron content from 0.42% up to 1.66%, yield strength increases and ductility decreases; this effect is enhanced by the sintering temperature because of the structural coarsening. Both ultrafine grained and nanostructured materials have a dimpled ductile fracture. On increasing the crystallite size, a mixed dimpled-cleavage fracture is observed.     

不锈钢纤维多孔材料拉伸性能研究

以316L不锈钢纤维毡为原料,采用不同的烧结工艺,制备出孔隙度为70%~95%的不锈钢纤维多孔材料,研究了纤维丝径、孔隙度、烧结温度和保温时间对其拉伸性能的影响。研究表明,不锈钢纤维多孔材料的拉伸过程主要分为3个阶段:弹性阶段、塑性变形阶段和断裂阶段。纤维越细,多孔材料的抗拉强度越高;随着孔隙度的增加,多孔材料的抗拉强度逐渐降低;提高烧结温度或延长保温时间,均会提高多孔材料的抗拉强度。     

Effect of Fe-based pre-alloyed powder on the microstructure and holding strength of impregnated diamond bit matrix

An iron-rich pre-alloyed powder was selected out, and the pre-alloying degree of matrix materials and the sintering temperature were considered to investigate the effect of the Fe-based pre-alloyed powder on the microstructure and holding strength of impregnated diamond bit matrix. And relative density and bending strength of the specimens were measured, and then the resulting fracture surfaces were analyzed using scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The results showed that the relative density, bending strength and plasticity of matrix materials are increased with the sintering temperature and the pre-alloying degree. The influence of the pre-alloying degree on them is more significant than that of the sintering temperature within the experimental parameters. Besides, Fe-based matrices have thermal corrosion effect on diamonds at high temperature sintering process. And the rate of diamond graphitization has a greatly increase with the sintering temperature changes from 900 °C to 1020 °C and the holding strength decreases. A low pre-alloying degree accelerates the rate of diamond graphitization. But an adequate pre-alloying degree of Fe-based matrix materials is conducive to improve the wettability of the matrix to diamonds, alleviate the diamond graphitization, reduce the diamonds' thermal damage and improve the holding strength. Besides, it can also greatly reduce the sintering temperature and broaden the sintering temperature range. In a word, it is feasible and reasonable that Fe-based pre-alloyed powders replace Fe elemental powders to fabricate impregnated diamond bits. And it has a good economic value and broad application prospect.     

莫来石纤维对氧化铝陶瓷性能的影响

选用莫来石纤维为增强体,通过添加适量的烧结助剂,制备莫来石纤维增强氧化铝陶瓷基复合材料,探讨了不同烧结温度和不同纤维含量对复合材料性能的影响规律.结果表明:莫来石纤维增强氧化铝陶瓷基复合材料的相对密度、弯曲强度和断裂韧性随烧结温度和纤维含量的增加先增大后减小,当烧结温度为1450 ℃、纤维含量为15%时,复合材料的弯曲强度、断裂韧性最高,复合材料弯曲强度和断裂韧性分别达到502.36 MPa和3.48 MPa·m~(1/2),比基体材料分别提高63.8%和54.7%;相对密度达到98.41%.纤维的拔出和脱粘消耗了大量的能量,是莫来石纤维增强氧化铝陶瓷复合材料力学性能提高的主要原因.     

Ag-Cu固溶体颗粒制备及低温烧结互连接头性能

通过液相化学还原法制备Ag-Cu固溶体纳米颗粒,采用低温热压烧结工艺制备“三明治”结构的互连接头.采用X射线衍射仪对所制备的Ag-Cu固溶体纳米颗粒及烧结体进行物相表征;采用能谱仪对所制备的Ag-Cu固溶体纳米颗粒的元素进行表征;采用纳米粒度仪对Ag-Cu固溶体纳米颗粒粒径进行表征;通过扫描电子显微镜对互连接头的烧结组织和剪切断面形貌进行观察,分析颗粒烧结情况和互连接头断裂模式. 结果表明,通过液相化学还原的方法实现了室温下铜在银中的超饱和固溶,其中Ag原子分数为62.29%,Cu原子分数为37.71%,远超常温下常规块体材料的固溶度. 所制备的纳米颗粒在250 ℃以内保持相对稳定的固溶体相,260 ℃时发生相分离. 当烧结温度为300 ℃、烧结压力20 MPa时,所获得的互连接头具有优异的力学性能,平均抗剪强度达到105 MPa,且烧结组织呈现完整的脉络状,剪切断面全部为韧窝状,属于韧性断裂.     

Understanding the potential of microwave sintering on WC - Co

Tungsten-rich cemented carbides are known for their excellent features in terms of balancing strength, durability, wear resistance and fracture toughness. Conventional sintering has been widely used to manufacture these strong and hard materials, even with its shortcomings in manufacturing time, energy requirement and strength threshold, paving way for a number of new and enhanced processing techniques aimed at developing high performance carbide tools. Microwave sintering has been successfully applied to a range of materials, including ceramics and a broad series of refractory metals. This study used microwave sintering to manufacture high-strength WC-Co alloys requiring significantly less time and processing steps, and without grain growth inhibitors as part of the composition. Particles, sized between 100 and 500 nm, were compacted using a conventional, unidirectional press at room temperature to create loosely bonded green samples that were later microwave sintered. The effect of sintering temperature and initial particle size, and how each of these influences the microwave behaviour for such range of materials, are also discussed. The maximum demonstrated hardness in submicron samples was 1800 HV, which is 20% larger than most industrial cutting tools manufactured using conventional routes. Fracture toughness was calculated from combining the hardness results and crack length measurements. Submicron particles exhibited great fracture toughness with a maximum of 14 MPa√m, which is impressive considering the high hardness achieved in these samples. The samples with enhanced mechanical behaviour, including hardness and fracture toughness, demonstrated homogeneity in grain size, grain growth and WC-Co bonding.     

Properties and microstructural evolution of W-Ni-Fe alloy via microwave sintering

The mechanical properties and microstructure evolution of 93W-4.9Ni-2.1Fe (wt.%) alloys were investigated via microwave sintering. The microwave sintering promoted the dissolution and diffusion of tungsten atoms in the matrix phase and strengthened sintering activity. With the increase of microwave sintering temperature, pores in the alloy were reduced and gradually eliminated, tungsten grains coarsened, the distribution of tungsten grains and matrix phase became more homogeneous, and the fracture mode transformed from intergranular fracture to tungsten transgranular cleavage fracture, respectively. The W-matrix interfacial bond strength of 93W-4.9Ni-2.1Fe was enhanced and the mechanical properties were significantly improved with the increase of sintering temperature.     

Ti(C,N)基金属陶瓷材料显微结构与性能研究进展

对国内外近年来有关Ti(C,N)基金属陶瓷材料的显微结构与性能的研究成果进行了总结。首先,介绍了Ti(C,N)基金属陶瓷材料的发展史;Ti(C,N)基金属陶瓷的显微结构、力学性能,以及显微结构与其性能的关系等。其次,列举并比较了不同的烧结方法所制备的Ti(C,N)基金属陶瓷材料的力学性能;结果表明:微波烧结和放电等离子烧结技术在较低的温度就可以成功烧结高硬度、高抗弯强度与断裂韧性高的产品,但实际生产中,这类技术还没有广泛被应用,应用最广的是真空烧结方法。最后介绍了Ti(C,N)基金属陶瓷材料的今后的研究趋势。     

Effects of sintering temperature on fine-grained tungsten heavy alloy produced by high-energy ball milling assisted spark plasma sintering

Fine-grained tungsten heavy alloys (WHAs) were successfully produced using the high-energy ball milling assisted spark plasma sintering (SPS) method. The effects of increasing sintering temperatures on the microstructure and mechanical properties of the alloy were studied in detail. The hardness of the alloy was found to continuously decrease from 79.3 to 63.8 HRA. In contrast, the bending strength continuously increased from 353.6 to 954.5 MPa. W grain size increased with increased sintering temperature. The temperature ranges from 1000 to 1100 °C and 1150 to 1200 °C were a period of rapid growth of W grain. According to the color change in the scanning electron microscope (SEM) image, the W alloy microstructure were classified into white W grains, off-white W-rich particles, dark grey matrix γ-(Ni, Fe, W), as well as pitch-black W- and O-rich particles. The bending fracture of the alloy mainly displays the features of intergranular fracture. The microporosity of different sizes was distributed on the bending fracture, and grew with increased sintering temperature.     

微波烧结ZrO_(2(n))/Al_2O_3复合陶瓷工艺与组织

以纳米ZrO2、微米Al2O3为原料,采用微波烧结方式制备ZrO2/Al2O3复相陶瓷。探讨了烧结温度和保温时间对试样线收缩率、相对体积密度、硬度和断裂韧性的影响。结果表明,烧结温度1550℃,保温时间10 min,可得到较高的硬度(13 350 MPa)和较好的断裂韧度(6.41 MPa.m1/2),烧结过程中发生了m-ZrO2转变为t-ZrO2相变,nano-ZrO2的加入使Al2O3形成內晶型结构;试样的断裂方式为沿晶断裂和穿晶断裂并存;ZrO/AlO复合陶瓷主要通过应力诱导相变和内晶型结构进行增韧。