(Ti,V)C钢结硬质合金的烧结行为及物相分析

以钛粉、钒铁粉、碳粉、铬铁粉、钼铁粉和铁粉为原料,用原位烧结法制备了(Ti,V)C钢结硬质合金.利用XRD、SEM和EDS对相组成、组织结构和微区成分进行了分析.结果表明:最佳烧结时间是1h,(Ti,V)C钢结硬质合金的最佳烧结温度是1400 ℃,TiC的最佳烧结温度是1420 ℃.TiC/(Ti,V)C钢结硬质合金的主要相组成为TiC/(Ti,V)C、α-Fe、Fe3C、(Cr,Fe)7C3,与TiC硬质相颗粒相比,(Ti,V)C颗粒形态更加圆整.     

TiC/耐热钢钢结硬质合金原位反应合成研究

以钛铁粉、铬铁粉、铁粉、胶体石墨等为原料，原位反应合成了TiC/耐热钢钢结硬质合金，并用扫描电镜(SEM)、X射线衍射等测试方法对所制备的试样进行了组织结构分析。研究结果表明：反应合成的钢结硬质合金主要相组成为TiC Fe—Cr固熔体，所合成的硬质相TiC颗粒细小，随烧结温度升高TiC颗粒略有长大。当加入一定的钼与硼后，钢结硬质合金硬度和致密度提高，TiC颗粒尺寸减小，分布更均匀。     

TiC/Cr18Ni8钢结硬质合金的制备及硼与钼对其组织和性能的影响

以钛铁粉、铬铁粉、铁粉、胶体石墨等为原料,原位反应合成了TiC/不锈钢钢结硬质合金,并用扫描电镜(SEM)、X射线衍射等测试方法对所制备的试样进行了组织结构分析.研究结果表明钢结硬质合金主要相组成为TiC+Fe-Cr-Ni固熔体,TiC颗粒较为细小,形状较为规则,最大约2μm,大部分在1 μm以下.随烧结温度升高,钢结硬质合金的密度和硬度增加,添加硼和钼提高了钢结硬质合金的密度和硬度.     

新型(Ti,V)C钢结硬质合金的制备及性能分析

以钛粉、钒铁粉、碳粉、铬铁粉、钼铁粉和铁粉为原料,用原位烧结法制备了(Ti,V)C钢结硬质合金.利用XRD、SEM和EDS等检测手段对合金的相组成、组织结构和微区成分进行了分析,并测定了合金试样的抗弯强度.结果表明:合金增强相(Ti,V)C的形态比TiC更为规则、圆整,合金具有较高的抗弯强度,断口形貌特征为硬质相解理、基体准解理及韧窝.     

TiC含量对钢结硬质合金组织和性能的影响

以雾化铁粉为粘结相、TiC颗粒为硬质相,通过球磨、模压成形、真空烧结制备钢结硬质合金。研究表明,通过1 350℃真空烧结,钢结硬质合金致密化程度较好,组织和性能达到预期效果。随着TiC含量升高,钢结硬质合金晶粒的规则性和均匀性提高,密度和抗弯强度降低,硬度增加。当TiC含量为50%时,合金密度和抗弯强度达到最高,分别为6.11g/cm3和1 579.48 MPa;当TiC含量为60%时,合金硬度最高,为HRC86.3。     

TiC/ZrC添加量对TiC基钢结硬质合金组织与性能的影响

以TiC、ZrC为硬质相,加入Mo、Ni、C等元素,采用粉末冶金的方法制备了复合TiC-ZrC钢结硬质合金,研究了不同TiC/ZrC质量比对TiC基钢结硬质合金组织与性能的影响。采用扫描电镜对硬质合金试样组织进行了分析,并采用维氏硬度计、万能电子试验机等分别对试样的硬度、抗弯强度等力学性能进行了检测。结果表明:当TiC/ZrC质量比为4/1时,TiC颗粒上出现较多(Ti, Mo, Zr)C壳相,随着TiC/ZrC质量比降低,(Ti, Mo, Zr)C壳相数量减少。当TiC/ZrC质量比为4/1时,合金中的TiC颗粒细小,分布均匀,力学性能最佳,硬度、抗弯强度分别为847.2 HV_(10)、444.5 MPa。随TiC/ZrC质量比降低,合金中ZrC晶粒发生聚集,致使合金力学性能下降。     

粘结相对原位合成TiC钢结硬质合金组织结构和性能的影响

以钛铁粉、铬铁粉、铁粉、胶体石墨和镍粉等为原料,原位合成了TiC/Cr18Ni8、TiC/Cr19Al3和TiC/Ni40钢结硬质合金,并用扫描电镜、X射线衍射仪和洛氏硬度计、拉力试验机等对不同粘结相所制备的试样进行了组织结构分析和物理力学性能检测.结果表明:钢结硬质合金主要相组成为TiC、Fe-Cr-Ni和Fe-Cr固溶体,TiC晶粒细小,形状较为规则;粘结相对原位反应合成的钢结硬质合金的密度、硬度和所合成的TiC晶粒有较大影响,在相同烧结条件下TiC/Ni40钢结硬质合金的密度和硬度比TiC/Cr18Ni8和TiC/Cr19Al3钢结硬质合金的高,但TiC/Ni40钢结硬质合金中所合成的TiC晶粒比TiC/Cr18Ni8和TiC/Cr19Al3钢结硬质合金中合成的TiC晶粒偏聚现象严重.TiC/Ni40钢结硬质合金的硬度为60～70.5HRC,TiC/Cr18Ni8和TiC/Cr19Al3钢结硬质合金的硬度多在20～50HRC之间.三者的抗弯强度为960～1452MPa.     

TiC?NiCrCoMo钢结硬质合金的制备与高温氧化性能

以镍基合金（NiCrCoMo）为粘结相,以碳化钛（TiC）为硬质相,通过粉末冶金技术制备出抗高温氧化的TiC?NiCrCoMo钢结硬质合金。通过优化烧结工艺得到综合性能最佳的TiC?NiCrCoMo钢结硬质合金,测定了钢结硬质合金在不同温度下的氧化动力学曲线,并分析了氧化层的显微形貌。结果表明,经1280 ℃烧结的TiC?NiCrCoMo钢结硬质合金综合性能最佳,密度为6.01 g/cm3,硬度为HRC 65,抗弯强度为1100 MPa。随着氧化温度的升高,TiC?NiCrCoMo钢结硬质合金的氧化程度明显增加;通过与316L不锈钢钢结硬质合金的氧化动力学曲线对比发现,TiC?NiCrCoMo钢结硬质合金具有优异的抗高温氧化性能。     

原位烧结合成(Ti,V)C颗粒增强铁基复合材料的微观结构研究

将粉末冶金技术和原位反应技术相结合,制备了不同V/Ti原子比的 (Ti,V)C/Fe复合材料(V/Ti=0,0.4,0.6,0.8).用扫描电镜(SEM)、X射线衍射等测试方法对制备的复合材料进行了组织结构及相组成分析,用洛氏硬度计测试试样的硬度.研究结果表明:所制备的复合材料致密化好,硬度达60～65HRC,(Ti,V)C/Fe增强相颗粒尺寸大部分小于2μm,且随着V/Ti比的提高,(Ti,V)C的面间距和晶格常数相对TiC减小,(Ti,V)C增强相颗粒形态更规则,趋于球形.V/Ti为0.4时(Ti,V)C/Fe复合材料具备更好的微观结构.     

原位自生TiB+TiC增强Ti-Fe基复合材料微观组织和力学性能研究

以Ti粉、Fe粉和B_4C粉末为原料,采用冷等静压+高真空烧结方法制备了不同(TiB+TiC)增强相体积分数的Ti-Fe合金基复合材料(Fe元素质量分数为5%～15%),重点讨论了Fe含量和增强相对复合材料微观组织和力学性能的影响规律。结果表明,在1 150～1 250℃烧结温度下制备出Ti-Fe合金基复合材料致密度随Fe含量与增强相体积分数升高而降低。Fe含量增加使基体中α相层片状结构细化,而B_4C粉末的添加生成原位自生TiC颗粒和TiB纤维增强相,基体结构由层片状转变为等轴状。材料力学性能随Fe含量和增强相体积分数增加而提高。在1 150℃烧结制备的Ti-15%Fe-10vol%(TiB+TiC)复合材料硬度(HV)达到334,抗压强度达到2 040 MPa。     

Microwave Heating, Isothermal Sintering, and Mechanical Properties of Powder Metallurgy Titanium and Titanium Alloys

This article presents a detailed assessment of microwave (MW) heating, isothermal sintering, and the resulting tensile properties of commercially pure Ti (CP-Ti), Ti-6Al-4V, and Ti-10V-2Fe-3Al (wt pct), by comparison with those fabricated by conventional vacuum sintering. The potential of MW sintering for titanium fabrication is evaluated accordingly. Pure MW radiation is capable of heating titanium powder to ≥1573 K (1300 °C), but the heating response is erratic and difficult to reproduce. In contrast, the use of SiC MW susceptors ensures rapid, consistent, and controllable MW heating of titanium powder. MW sintering can consolidate CP-Ti and Ti alloys compacted from ?100 mesh hydride-dehydride (HDH) Ti powder to ~95.0 pct theoretical density (TD) at 1573 K (1300 °C), but no accelerated isothermal sintering has been observed over conventional practice. Significant interstitial contamination occurred from the Al₂O₃-SiC insulation–susceptor package, despite the high vacuum used (≤4.0 × 10^?3 Pa). This leads to erratic mechanical properties including poor tensile ductility. The use of Ti sponge as impurity (O, N, C, and Si) absorbers can effectively eliminate this problem and ensure good-to-excellent tensile properties for MW-sintered CP-Ti, Ti-10V-2Fe-3Al, and Ti-6Al-4V. The mechanisms behind various observations are discussed. The prime benefit of MW sintering of Ti powder is rapid heating. MW sintering of Ti powder is suitable for the fabrication of small titanium parts or titanium preforms for subsequent thermomechanical processing.     

THE CORRELATION BETWEEN RAW MATERIALS,PREPARATION CONDITIONS,AND PROPERTIES OF SINTERED IRON

Abstract

Three plain iron powders of different types (sponge-iron, atomized and electrolytic iron powder) were studied with respect to their sintering behaviour and to the influence of manufacturing parameters—i.e., compacting pressure, sintering temperature, and sintering atmosphere—on the microstructure and the properties of sintered compacts. The changes of length, electric conductivity, and strength during sintering are explained in physical and chemical terms. Technical sintering diagrams are presented. The influence of sintering atmospheres on the mechanical properties of sintered compacts is shown for the three types of powder. The correlation between pore structure and strength is discussed; analytical relationships are developed which are in agreement with the experimental results.     

Fe-Mo-B Enhanced Sintering of P/M 316L Stainless Steel

Liquid-phase enhanced sintering of powder metallurgy（P/M）316L stainless steel by addition of sintering aids was studied.2%-8% of pre-alloyed Fe-Mo-B powder with two different particle sizes was added as sintering aids,and the specimens were sintered in vacuum at 1 200-1 350 ℃.The results show that the fine Fe-Mo-B powder（5-10 μm）has stronger activated effect.The sintered density increases with the increase in sintering aid content or sintering temperature.Warm compaction has a better effect on the control of dimensional precision of compacts.The prealloyed Fe-Mo-B powder deviated from Mo2FeB2 component can also be sintering aid of P/M 316L stainless steel.     

Sintering of loose cobalt,nickel, and iron powders in a magnetic field

Conclusions The action of volume magnetic forces markedly surpassing volume gravitational forces on a disperse ferromagnetic system strongly intensifies the densification of the powder during sintering. The substantial improvement in physical properties exhibited by porous specimens after magnetic sintering indicates a higher degree of perfection of interparticle contacts, resulting from the intensification of densification achieved during sintering in a magnetic field, and, possibly, an anisotropic arrangement of powder in a magnetic field.Translated from Poroshkovaya Metallurgiya, No. 1(229), pp. 33–37, January, 1982.     

配加澳大利亚MacTM粉矿的烧结杯试验

进行了烧结混匀料配加澳大利亚MacTM粉矿的试验,增大MacTM粉矿配比烧结矿转鼓强度和成品率没有明显变差,但需要增大烧结料水分以保证较高的成球率;由于MacTM粉矿含有5%左右的结晶水、烧损较高,随其配比加大,烧结矿的烧成率逐步下降.     

SINTERING KINETICS OF OXIDE-FILMCOATED COPPER POWDER

Abstract

The sintering kinetics of pure copper powder and of copper powder coated with a critical oxide (CU₂O) film thickness (～,500Å), has been studied by following the densification of the compacts as a function of temperature and time in pure dry hydrogen and in vacuum. The activation energy for the sintering of pure copper powder in hydrogen was 55,000 cal/mole, suggesting that the volume self-diffusion mechanism predominates during the sintering process. In the case of the oxide-coated powder the corresponding value was 37,000 cal/mole. The high rate of sintering of the coated powder in hydrogen and in vacuum is explained in terms of an activated sintering mechanism.     

烧结过滤材料使用性能与粉末粒度及烧结工艺的关系

本文从理论推导和实验数据探讨了松装烧结过滤材料使用性能(过滤精度、过滤效率)与原料粉末粒度、粒度组成及烧结工艺参数(烧结温度)之间的数学关系。运用多项式回归方法和微机分析处理,建立了相应的数学模型。从而为合理选择原料粉末粒度和最佳烧结工艺参数以制取符合预定使用性能要求的过滤材料提供了理论和实验依据。在一定条件下,数学模型对制取粉末冶金多孔材料具有指导意义。     

Plastic deformation,recrystallization, and sintering of nickel and tungsten powders subjected to vibratory milling

Conclusions Prior plastic working of powder particles may either activate or deactivate the recrystallization and sintering processes, depending on the nature of the mechanical action to which they are subjected, the physical properties of the material of the powder, the starting condition of the particles, and the type of the dislocation structure forming during the plastic working. In the nickel powder investigated, which in the starting condition is characterized by a comparatively high density of dislocations and is a ductile material, the level of stress and temperature generated during vibratory milling leads to the formation of a dislocation structure impeding the recrystallization and sintering processes. With the tungsten powder investigated, which has a comparatively low starting density of dislocations and a high shear stress, vibratory milling results in the formation of a dislocation structure which activates both the recrystallization and sintering processes. Prolonged vibratory milling of tungsten gives rise also to the formation of a polygonized structure hindering the thermally activated recrystallization and sintering processes.Translated from Poroshkovaya Metallurgiya, No. 9 (189), pp. 7–15, September, 1978.     

致密化工艺对氧化钛粉末及等离子喷涂涂层性能影响研究

采用喷雾干燥法制备了一种球形氧化钛团聚粉末, 并通过高温烧结及感应等离子球化工艺对团聚粉末进行 致密化处理。 利用扫描电子显微镜 (SEM)、 霍尔流速计和粉末颗粒强度仪对粉末性能进行了表征, 研究了不同致 密化处理工艺对粉末颗粒强度、 松装密度及流动性的影响。 采用大气等离子喷涂 (APS) 工艺制备了氧化钛涂层, 并对涂层的微观组织进行研究。 研究结果表明, 高温烧结工艺及等离子球化工艺均可有效提升氧化钛团聚粉末 的致密度, 经过高温烧结工艺后氧化钛粉末内部的细小颗粒呈现烧结熔融的趋势, 而采用等离子球化处理后的 团聚粉末直接形成了致密球体结构。 相比于高温烧结工艺, 等离子球化工艺对氧化钛粉末的致密化效应更为明 显, 粉末的颗粒强度可达 187.86 MPa, 松装密度可由 0.79 g/cm3 提升至 1.69 g/cm3, 流动性由 163.22 s/50g 加快 至 100.27 s/50g。 该粉末经过大气等离子喷涂沉积形成的氧化钛涂层孔隙率为 2.8 %, 与未经致密化工艺处理的氧 化钛团聚粉末相比, 制备的涂层致密化水平有了较大程度的提升, 涂层的平均显微硬度值由 434.18 HV0.3 提升至 744.37 HV0.3, 涂层的结合强度均值由 11.07 MPa 提升至 29.93 MPa。