锆英石对镁钙质耐火材料性能的影响

镁钙质耐火材料是一种强碱性耐火材料,对碱性炉渣和钢液具有良好的化学稳定性,且有利于钢液的脱磷、脱硫,以及钢液的净化,但由于CaO的易水化性使镁钙质耐火材料的使用受到了限制。实验选用6种不同锆英石的加入量,采用两种不同的烧结方案,对添加锆英石后的镁钙质耐火材料的性能进行了研究。结果表明,添加锆英石后的镁钙质耐火材料烧结性能提高,显气孔率降低,体积密度增大,荷重软化温度提高,抗渣性增强。     

热挤压对SiCw／MB15镁基复合材料组织和性能的影响

利用SEM，TEM，X射线衍射仪等方法，研究了挤压对SiCw／MB15镁基复合材料组织和性能的影响。结果表明：热挤压后复合材料组织更加均匀，SiC晶须长轴与挤压方向平行，晶须的增强作用得到了充分的发挥，显著提高了SiCw／MB15镁基复合材料的力学性能。     

镁基复合材料的阻尼性能研究

随着人们对环保和能源问题的关注,镁基复合材料的研究成为材料领域的热点.本文综述了镁基复合材料阻尼性能研究的现状、镁基复合材料阻尼性能的机制,以期对镁基复合材料阻尼性能的研究有所裨益.     

表面涂覆对碳纤维镁基复合材料组织与性能的影响

通过溶胶凝胶法在短切碳纤维表面涂覆了 MgO、Siθ2、Tiθ2涂层,分析了各涂层对碳纤维润湿性能的影响,制备了镁基复合材料,研究了碳纤维表面涂覆对镁基复合材料组织和性能的影响规律.结果表明,MgO涂层表面较为粗糙,存在团聚的MgO颗粒,Siθ2、Tiθ2涂层表面较为光洁,沿碳纤维径向连续分布,具有良好的仿形性.而且3...     

锆含量对镁锌合金晶粒度的影响

研究了锆含量对镁锌合金晶粒度的影响。结果表明,在镁锌合金中添加锆能细化镁锌合金的晶粒度,添加量为0.6%时,镁锌合金的晶粒度从145μm细化到42μm。晶粒细化后材料的伸长率从5.3%提高到9.3%,抗拉强度从149 MPa提高到169 MPa,硬度从76.3 HB提高为86.3 HB。     

不同涂层碳纳米管对增强镁基复合材料力学性能的影响

采用化学镀的方法在用化学气相沉积法(CVD)制备的一维多壁碳纳米管(MWNTs)上化学镀镍、镍-锌处理,然后在氩气的保护下,采用搅拌铸造的方法与镁复合,制得碳纳米管增强镁基复合材料.在MTS电液伺服机上对其抗拉强度和伸长率进行了测试,同时,采用TEM和SEM方法对复合材料的微观组织和机构进行分析.试验结果表明:随着碳纳米管含量的增加,复合材料的抗拉强度和伸长率逐渐提高,当镀镍碳纳米管的体积百分数达到1.0%时,抗拉强度和伸长率分别提高了105%和96%;相应的镀镍锌的碳纳米管复合材料则分别提高了124%和107%,但当碳纳米管的含量达到1.5%时,抗拉强度和伸长率都明显的降低.     

热处理对SiCp/AZ61镁基纳米复合材料阻尼性能的影响

实验采用自行设计的高能超声装置制备SiCp/AZ61镁基纳米复合材料(MMNCS),并对制备的复合材料进行了阻尼性能测试。研究时效处理(T5)、固溶处理(T4)及固溶后时效处理(T6)3种不同热处理工艺,对挤压态n-SiCp/AZ61 MMNCs阻尼性能的影响。研究表明,不同的热处理工艺对n-SiCP/AZ61复合材料阻尼性能的影响较显著。与挤压态的n-SiCP/AZ61复合材料相比,T4态和T6态与应变相关部分的阻尼得到了较大幅度提升。在T6态时,随着时效时间的延长,复合材料的阻尼性能下降。不同热处理工艺对AZ61镁合金阻尼性能的影响规律,室温可通过G-L理论,高温时可由界面阻尼机制很好的解释。     

利用搅拌铸造结合超声处理法制备镁基复合材料

在目前的研究中,利用搅拌铸造结合超声处理方法成功地制备出了不同体积分数(5vol%和10vol%)的微米颗粒增强的AZ31B镁基复合材料。利用350℃,12:1的挤压比对铸锭进行了挤压处理。利用金相和扫描电子显微镜对复合材料的微观结构进行了研究。复合材料的微观结构显示,增强体具有相对均匀的分布且晶粒获得了显著的细化。微米碳化硅颗粒的存在可以显著的提高基体合金的显微硬度﹑弹性模量以及抗拉伸强度。此外,复合材料的显微硬度﹑弹性模量以及抗拉伸强度随着微米颗粒含量的增加而增加。     

低温反应自熔制备Mg基复合材料的组织与性能

采用一种新的合成方法——低温反应自熔制备了10vol％钛合金(Ti-6Al-4V)颗粒增强的镁基复合材料。利用光镜和扫描电镜(SEM)观察了复合材料的显微组织，并通过X射线衍射和拉伸试验对其相结构和室温力学性能进行了探讨。结果表明，复合材料的基体晶粒细小、增强体和合金元素分布均匀、基体镁颗粒间的氧化膜得到了有效的破碎和分散，同时．所制备复合材料的强度和延伸率明显高于粉末冶金法。     

BN与LPSO相混杂增强的镁基复合材料制备及性能

研究了六方氮化硼(h-BN)颗粒增强镁基复合材料的制备工艺及其性能。通过化学镀法在h-BN颗粒表面包覆一层纯镍,镀镍处理能显著改善h-BN与镁合金熔体的润湿性,改善其与基体的界面结合。通过向基体合金中加入Y元素,利用镀镍层熔入熔体中的Ni获得了由Mg-Ni-Y组成的LPSO结构(长周期堆垛有序结构),制得了h-BN+LPSO混杂增强的镁基复合材料。超声处理后,hBN增强相体积分数为3%的镁基复合材料热导率为99.92W/(m·K),室温(RT)至100℃的平均热膨胀系数为18.36×10^-6K^-1,抗拉强度为171MPa,伸长率为3.9%,获得了兼具较高力学性能和优异热物性能的镁合金材料。     

热处理对Ni-P-SiO2复合镀层性能的影响

进行了Ni-P-SiO2化学复合镀试验,选取不同加热温度和保温时间对所制备的复合镀层进行热处理.利用XJP-6A型金相显微镜,HVS1000型数显显微硬度计和贴滤纸法对热处理后的复合镀层的显微组织、硬度和孔隙率进行了研究.结果表明,在400 ℃加热保温90 min后,Ni-P-SiO2复合镀层组织更均匀致密,与基体的结合良好,硬度更高,孔隙率几乎为零.     

Chemical synthesis of nanocrystalline ZrO_2-SnO_2 composite powders

ZrO_2-SnO_2 composite nanoparticles were prepared by heating the hydrate precursors synthesized by the chemicalco-precipitation reaction of ZrOCl_2 and SnCl_4. The precursors were examined by differential thermal analysis (DTA) andthermogravimetric analysis (TGA). The composite powder was characterized using X-ray diffraction (XRD), transmissionelectron microscopy (TEM) and desorption isotherm (Barrett-Joyner-Halenda method). The average crystal size of thenanoparticle ranges from 15 to 30 nm for the sample containing 5%-25% ZrO_2 (mass fraction). Most of the pores in theZrO_2-SnO_2 nanoparticles are about 10-20 nm in diameter. The composite powder is promising for chemical sensors.     

Synthesis of ZrO2-SiC composite powder and effect of its addition on properties of Al2O3-C refractories

ZrO2-SiC composite powder was synthesized by carbothermal reduction of zircon in argon atmosphere, and it was used as the additive to prepare Al2O3-C refractories. The effects of heating temperature on the synthesis process and the addition of the synthesized composite powder on the properties of the Al2O3-C refractories were investigated. The results show that the synthesized composite powder can be easily obtained by heating the mixture of zircon and carbon black at 1 873 K for 4 h in argon atmosphere, and the relative contents of ZrO2 and SiC in sample reach about 83.7% and 16.3%, respectively. The bulk density, crushing strength and thermal shock resistance of the Al2O3-C refractories can be improved obviously by the addition of the synthesized ZrO2-SiC composite powder.     

Mechanical properties of MgO–Al2O3–SiO2 glass-infiltrated Al2O3–ZrO2 composite

This work attempts to improve the mechanical properties of alumina-10 wt% zirconia (3 mol% yttria stabilized) composite by infiltrating a glass (magnesium aluminum silicate glass) of lower thermal expansion on the surface at high temperature. The glass improved the strength of the composite at room temperature as well as at higher temperatures. There was a significant improvement in the Weibull modulus after the glass infiltration. Glass-infiltrated samples showed better thermal shock resistance. The magnitude of strength increment was found to be in the order of the surface residual stress generated by thermo-elastic properties mismatch between the composite and the infiltrated glass.     

阴极等离子电解沉积ZrO_2-Al_2O_3-Pt复合热障涂层组织及特性

采用在阴极区添加陶瓷微珠进行阴极等离子电解的方法,可以在大面积的高温合金上沉积ZrO2-5%Al2O3弥散Pt微粒的复合热障涂层。SEM形貌观测结果表明,涂层的内层为致密结构,外层为多孔结构,涂层厚度可达200μm。XRD分析结果表明,该涂层由t-ZrO2、c-ZrO2、α-Al2O3。在1100℃空气中循环氧化结果表明,随着Pt含量的增加,ZrO2-5%Al2O3弥散Pt微粒的复合热障涂层抗高温氧化性能和抗剥落性能显著提高,隔热实验证明该涂层具有优异的隔热性能。这些优异的性能可归于弥散Pt微粒的增韧效应,垂直闭塞微孔可以松弛应力的效应。     

ttao相结构对ZrO2陶瓷透光度的影响

研究了相结构对ZrO₂陶瓷透光度的影响。本文制备了3 mol%Y₂O₃稳定ZrO₂(3YSZ)和5 mol%Y₂O₃稳定ZrO₂(5YSZ),分别在1450℃、1500℃、1550℃下烧结,通过XRD、SEM、EMPA等研究了3YSZ和5YSZ相结构和相含量,用UV-Vis分光光度计测试其在可见光范围内的透光率,探讨相结构和透光度的关系。结果表明,3YSZ和5YSZ均为稳定四方相 (t相)和亚稳定四方相 (t′相)的两相复合物,其中3YSZ以t相为主,且t相含量随烧结温度的升高而增加,透光性较差;5YSZ以t′为主,且t′相含量随烧结温度的升高而增加,透光性较好。得出结论,t相透光性较差,t′相透光性较好,并对此进行解释。     

ZrO2对Mo-Al2O3金属陶瓷性能的影响

对添加1．0％～5．0％（质量分数，下同）ZrO2的金属陶瓷强度测试表明，随着ZrO2含量的增加，材料的强度提高，添加量为3．5％时的材料强度达到最高，超过3．5％后材料强度呈下降趋势。材料中添加4％ZrO2的陶瓷晶粒比不含ZrO2的材料略大，但对材料的氧化趋势没有影响。含ZrO2的Mo-Al2O3金属陶瓷热电偶保护套管在N2保护下的1700℃左右比不含ZrO2的套管使用寿命长1倍以上。     

钛/铜中间层/钢扩散焊复合管界面组织与性能

以铜箔为中间层,采用拉拔—内压扩散法制备钛/钢复合管.利用光学显微镜、扫描电子显微镜、X-光衍射仪和能谱仪对界面组织、断口形貌和成分进行分析,通过剪切试验测定界面的结合强度.结果表明,以铜箔作中间层,拉拔—内压扩散法实现了钛/钢的冶金结合;在钛/铜界面处发生了明显的原子扩散,并形成不同的扩散层;随着扩散温度和时间的增加扩散层的厚度逐渐增加;中间层的加入阻止了固相扩散中钛铁、钛碳脆性化合物生成;钛/钢界面的抗剪强度随着扩散温度的升高先增加后降低,铜层的加入使抗剪强度明显提高,最高可达310 MPa.     

Thermal and mechanical properties of ZrO2-CeO2 plasma-sprayed coatings

The thermal and mechanical properties of ZrC₂-C_{eO 2}plasma-sprayed coatings were evaluated to examine their potential as a thermal barrier coating. ZrO₂-CeO₂ solid-solution powders containing up to 70 mol % CeO₂ are successfully plasma sprayed, but cerium content decreases during spraying due to the vaporization of cerium oxide. Hardness is greatest at 30 mol% CeO₂. With increased CeO₂ content, the thermal conductivity decreases to 0.5 W/m K and the thermal expansion coefficient increases to 12.5 x 10_-6 /K. Increased torch input power causes both the relative density and the hardness to increase monotonically, while the thermal conductivity and the thermal expansion coefficient are not significantly affected. When heated above 1300 K, the coating shrinks considerably due to sintering and its thermal conductivity increases abruptly.     

Investigation on microstructure and mechanical properties of diffusion bonded Al/Mg2Si metal matrix composite using copper interlayer

Diffusion bonding of Al/Mg₂Si metal matrix composite (MMC) using Cu interlayer at optimal bonding temperature of 540 °C for various bonding durations was investigated. This metal matrix composite (MMC) containing 15% Mg₂Si particles was produced by in situ technique. Specific diffusion bonding process was introduced as a low vacuum technique. The composition and microstructure of the joined areas were examined by X-ray diffraction (XRD) and scanning electron microscopy equipped with energy dispersive X-ray spectroscopy (EDS). Microhardness and shear tests were conducted to the samples to evaluate the effect of bonding duration on weldability. Several different diffusion layers exist at the bond region depending on the bonding duration. The shear strength of joints increased with bonding duration due to elimination of CuAl₂ brittle diffusion layer.