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本文通过对具有不同烧结密度的热压SiC—TiC复相陶瓷在氮气氛中进行热等静压后处理,从理论上(依据热力学数据)分析了闭合SiC—TiC复相陶瓷开孔孔隙的可能性,并用实验予以证实;同时,还研究和讨论了热等静压后处理工艺对陶瓷烧结体某些物理和力学性能(密度、强度和断裂韧性)以及氧化行为的影响。实验结果表明:SiC和TiC在高的氮气压力和温度下,可以分别氮化成Si_3N_4和TiN;对于预烧结相对密度约为95%的热压SiC—TiC复相陶瓷,在200MPa氮气压力下于1850℃氮化1小时后,室温强度由345MPa提高到686MPa,断裂韧性高达7.9MPa·m~(1/2),其抗氧化性能也有明显改善。 相似文献
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热等静压用陶瓷模的烧结 总被引:1,自引:0,他引:1
热等静压用陶瓷模要具有一定的室温强度,又要具有良好的高温塑性变形能力,因而需要采取特殊的烧结工艺,本工作分析了加热过程中陶瓷模中的物理,化学变化,设计了缓慢加热/冷却,分段保温的烧结方法。研究结果表明,陶瓷模材料中的SiO2颗粒在烧结过程中发生了多次晶型转变,并伴随着强烈的体积变化,采用设计的烧结方法,较好地控制晶型转变而引起的体积变化,避免了陶瓷模开裂或畸变,此外还发现,加入MgO和TiO2助烧 相似文献
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纯钒粉末通过预清洗、冷等静压(CIP)成形、热等静压(HIP)的工艺制备成纯钒块材,采用拉伸实验、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线结构衍射仪(XRD)等技术对其力学性能和微观组织结构进行了研究.结果表明:在1 200℃条件下,纯钒的强度、伸长率和密度随热等静压压力升高而增加,随热等静压保温时间延长而下降;在1 200℃/120MPa/1h工艺条件下制备的纯钒试样相对密度达99.7%,抗拉强度和伸长率分别达552MPa和20%.纯钒的晶粒结合紧密,呈单相,为板条状马氏体结构,其断裂方式以解理断裂为主. 相似文献
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热等静压工艺对硬质合金性能的影响 总被引:5,自引:0,他引:5
应用烧结加热等静压和烧结-热等静压两种工艺制备了粗晶WC-15Co、WC-22Co和微晶WC-12Co-1Cr3C2、中等晶粒WC-12Co硬质合金,从原理、经济性论述了这两种工艺的差异及其对WC-Co硬质合金组织和性能的影响。结果表明,烧结-热等静压制作的硬质合金孔洞消除了,并且硬质合金的抗弯强度和弯曲疲劳寿命也大幅度提高。 相似文献
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采用热等静压烧结法制备Mo–Na合金,研究了热等静压烧结温度对Mo–Na合金显微组织、硬度、密度及Na质量分数的影响,分析了Mo–Na合金热等静压烧结的致密化过程。结果表明:采用热等静压烧结法制备的Mo–Na合金显微组织细小均匀,平均晶粒尺寸在10 μm以下。随着热等静压烧结温度的升高,相对密度及硬度随之升高,在1100 ℃时达到最大,分别为99.58%和HRA 54.50,热等静压过程中液相的形成对Mo–Na合金的致密化起到了重要作用。热等静压过程很好地避免了低熔点Na金属高温烧结过程中的挥发,在1100 ℃烧结后Na质量分数基本无变化。 相似文献
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纳米/微米Al2O3-ZrO2内衬复相陶瓷的自蔓延高温合成 总被引:5,自引:1,他引:5
采用SHS重力分离技术制备出内衬Al2O3-ZrO2复相陶瓷.复相陶瓷基体主要由纤维状(Al2O3+ZrO2)共晶体组成,其中共晶体的ZrO2纤维直径达到纳米/微米尺度.经Vickers压痕法测试其断裂韧度为15.96MPa·m1/2,SEM观察和陶瓷材料断裂韧度测试得出裂纹的扩展主要受共晶体中Al2O3-ZrO2纳米/微米相增韧机制控制,迫使裂纹沿共晶体边界或层片共晶体Al2O3-ZrO2相界偏转,从而维持了该复相陶瓷较高的断裂韧度. 相似文献
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采用热等静压法制备铝基碳化硼复合材料(Al-B4C)板材,测试板材的密度和抗拉强度,并观察复合材料的微观组织和拉伸断口形貌。结果表明,Al-31%B4C(质量分数)板材的尺寸为3 mm×200 mm×5000 mm;Al-31%B4C复合材料的相对密度大于99.69%,抗拉强度大于300 MPa,断后延伸率大于3%,B4C颗粒均匀分布在基体中,并与基体紧密结合;Al-B4C复合材料板材的力学性能符合工程用中子吸收材料的要求。比较含不同质量分数B4C颗粒(10%、15%、20%、25%、30%、31%、35%、40%)的Al-B4C复合材料性能,当B4C质量分数为10%~40%时,随基体中B4C颗粒含量的增加,Al-B4C复合材料的密度和相对密度均逐渐降低;当B4C质量分数为10%~35%时,随基体中B4C颗粒含量的增加,Al-B4C复合材料的抗拉强度逐渐增大,断后延伸率逐渐降低。 相似文献
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机械球磨与烧结W基材料的组织与性能 总被引:1,自引:0,他引:1
采用机械球磨与热压工艺制备了W-TiC、W-Ni、W-CNTs(碳纳米管)和W-Ni-CNTs 4种W基材料。研究结果表明,机械球磨能显著降低复合粉的晶粒尺寸和增加晶格畸变。经机械球磨后热压的样品中W-TiC的致密度最好,密度达到18.36g/cm3;W-Ni和W-CNTs的密度分别为17.97g/cm3和18.23g/cm3,具有较好的致密性;W-Ni-CNTs样品密度为15.84g/cm3,致密度略低。微观组织分析表明:添加TiC粒子可以显著改善材料的烧结行为,但晶粒较大;添加少量Ni制备的样品,不仅致密度高,而且晶粒较小;添加CNTs可以改善W的烧结行为,同时能够抑制晶粒长大和对W晶界起到强化作用;同时添加Ni和CNTs样品的致密度较低,需要对Ni和CNTs的添加量及烧结工艺条件进一步优化。结合微观组织分析与显微硬度测试结果,发现W烧结体的显微硬度不仅和材料密度有关,而且和W晶粒大小及掺杂相有关。 相似文献
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采用热等静压(HIP)技术成形复杂结构的2A12铝合金粉末零件,基于MSC.MARC软件的Shima模型,使用2A12铝合金材料参数实现成形过程的数值模拟。模拟结果表明,特征结构狭缝处粉末体的相对密度呈现梯度分布,侧面的粉末体相对密度分布均匀;石墨模具基本没有变形。实验结果表明,石墨和铝粉末发生了界面反应,型腔内壁存在凹坑和凸起缺陷;粉末试样的规定塑性延伸强度和抗拉强度分别为179 MPa和316 MPa;断口形貌显示试样断裂起源于粉末界面连接处,由金相显微照片分析材料已经完全致密。 相似文献
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Hosam ElRakayby 《粉末冶金学》2017,60(4):293-300
Hot isostatic pressing of nickel-based superalloys has important applications for manufacturing near-net shape parts such as turbine disks and jet engine parts, which have to operate at high temperatures. Finite element modelling can be used to predict deformation and densification behaviour of such superalloys. Thus, the cost and time of trial and error to obtain the required geometry of the part can be reduced, such that near-net shape parts can be manufactured more economically. Numerical simulations were carried out by implementing the model of ElRakayby and Kim into Abaqus-FEA. The model parameters (relative density functions f and c) for the nickel-based superalloy were obtained from the creep response and compressive strength of porous and solid powder compacts at high a temperature. The agreement between finite element calculations and the experimental data was good for densification, shape change and density distribution of nickel-based superalloy during hot isostatic pressing. 相似文献
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ABSTRACTThe selective laser melting (SLM) process has gained considerable attention from industry and academia over the recent years. Furthermore, the hot isostatic pressing (HIP) technique has been widely applied as a post-treatment to increase the relative density of the fabricated parts. The main aim of this study is to investigate the effects of porosity elimination and mechanical properties on precipitation hardening stainless steel using SLM, HIP, solid-solution and aging treatments. This study also applied various laser scanning pitches (170, 210 and 250?μm), so that a significant phase transformation occurred between the SLM, HIP, solid-solution and aging treatments. The results showed that the laser scanning pitch was 170?μm, and after HIP, solid-solution and aging treatments the materials possessed optimal mechanical properties. The highest hardness (48.8?±?0.5 HRC) and TRS (2247.0?±?157.8?MPa) could be acquired. 相似文献
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《粉末冶金学》2013,56(3):455-462
AbstractMany industrial applications, e.g. processing of polymers, suffer from high costs caused by corrosion and wear. Particularly the combination of both increases the requirements for the materials used. Corrosion resistant cold work steels were developed to withstand the combined attack. Resistance is achieved by a sufficient content of chromium in the metal matrix and by carbides dispersed in a martensitic matrix. A further gain in wear resistance is possible by adding hard phases to the steel to produce a particulate reinforced metal matrix composite (MMC). The common consolidation process for such MMCs is hot isostatic pressing, but they can also be processed by solid state or liquid phase sintering. This work focuses on detailed investigations of the properties in dependence on the processing route. The results show that the resulting corrosion and wear resistance depend not only on the processing method, but also on the incorporated hard phases in combination with the manufacturing method. In addition, the unreinforced metal matrices were compared to the MMC. 相似文献