TiC-TiB2/MoSi2复合材料的制备及力学性能

以MoSi2、Ti和B4C粉为原料,采用高温热压技术原位合成不同体积百分数TiC-TiB2强韧化MoSi2复合材料,研究了TiC-TiB2颗粒对MoSi2基体材料显微组织结构和力学性能的影响.实验结果表明,采用MoSi2、Ti和B4C粉为原料进行热压原位合成是可行的.30%TIC-TiB2/MoSi2复合材料的抗弯强度和维氏硬度分别达到468.3 MPa和17 070,与纯MoSi2比较,分别增加了63.2%和83.5%.随着TiC-TiB2体积分数的增加,TiC-TiB2/MoSi2复合材料的晶粒大小明显细化,断裂方式由沿晶断裂为主向穿晶断裂为主转变,强化机制是细晶强化和弥散强化.     

添加剂镍对原位合成TiB2-TiC复相陶瓷材料性能的影响

用TiH2，Ni和B4C作为原料，采用热等静压法制备了TiB2-TiC复相陶瓷材料，此方法工艺简单。成本较低。XRD研究表明在样品中只存在TiB2和TiC两相；TEM研究结果表明TiB2晶粒为规则的多边形和板条状，添加剂Ni位于TiB2/TiC交界处；显微硬度、断裂韧性和SEM断口形貌的研究结果表明添加剂Ni显著提高了TiB2-TiC复相陶瓷材料的综合性能。     

ZrO2加入量对刚玉-尖晶石浇注料性能的影响

以板状刚玉(6～3 mm、3～1 mm和≤1 mm)为骨料,以电熔尖晶石细粉(≤0.044 mm)、白刚玉细粉(≤0.088mm和≤0.044 mm)、α-Al2O3微粉(≤5μm,d50=2.01μm)为基质,以纯铝酸钙水泥为结合剂,按骨料与基质的质量比为70∶30配料,以ZrO2等量代替白刚玉细粉(≤0.044 mm)制备刚玉-尖晶石浇注料,并研究ZrO2质量分数分别为0、2％、4％、6％、8％时对刚玉-尖晶石浇注料性能的影响.结果表明:随着ZrO2引入量的增大,试样的体积密度和显气孔率均呈上升趋势,线变化率逐渐增大,强度降低,高温抗折强度呈降低趋势,抗热震性和抗渣侵蚀性逐渐增强.综合考虑,ZrO2的最佳引入量为4％～6％.     

ZrO2强韧化MoSi2复合材料显微结构和性能

通过对热压合成制备的ZrO2 MoSi2复合材料显微组织及其断口形貌分析,结合硬度、抗弯强度、断裂韧度等力学性能和孔隙率、晶粒度的测试,初步探讨了ZrO2颗粒强韧化MoSi2复合材料的机制。结果表明,复合材料中ZrO2粒子沿着MoSi2晶界偏聚,抑制MoSi2晶粒长大;复合材料断口晶粒细小,裂纹扩展曲折,呈现出沿晶与穿晶的混合型断裂特性;ZrO2颗粒通过第二相强化和细化晶粒使复合材料强度得到提高,通过细化晶粒、裂纹偏转和分支、形成微裂纹等机制的综合作用增韧复合材料。     

油润滑下Al/MoSi2材料的摩擦学特性

运用M-200型磨损试验机测定了油润滑下Al/MoSi2材料的摩擦磨损性能，采用SEM和X射线观察与分析了摩擦副表面的形貌和相组成，探讨了磨损机制。结果表明：采用20#机油润滑可有效地提高Al/MoSi2材料的摩察磨损综合性能；与干摩擦状态相比，其摩擦系统和磨损率分别下降了40%和60%；油润滑时，Al/MoSi2材料的磨损机制主要表现为疲劳点蚀和磨粒磨损。     

Microstructural Evolution of Al-1Fe (Weight Percent) Alloy During Accumulative Continuous Extrusion Forming

As a new microstructure refining method, accumulative continuous extrusion forming (ACEF) cannot only refine metal matrix but also refine the phases that exist in it. In order to detect the refinements of grain and second phase during the process, Al-1Fe (wt pct) alloy was processed by ACEF, and the microstructural evolution was analyzed by electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM). Results revealed that the average grain size of Al-1Fe (wt pct) alloy decreased from 13 to 1.2 μm, and blocky Al₃Fe phase with an average length of 300 nm was granulated to Al₃Fe particle with an average diameter of 200 nm, after one pass of ACEF. Refinement of grain was attributed to continuous dynamic recrystallization (CDRX), and the granulation of Al₃Fe phase included the spheroidization resulting from deformation heat and the fragmentation caused by the coupling effects of strain and thermal effect. The spheroidization worked in almost the entire deformation process, while the fragmentation required strain accumulation. However, fragmentation contributed more than spheroidization. Al₃Fe particle stimulated the formation of substructure and retarded the migration of recrystallized grain boundary, but the effect of Al₃Fe phase on refinement of grain could only be determined by the contrastive investigation of Al-1Fe (wt pct) alloy and pure Al.     

双奇数相加的逻辑分析（五）

1　单点验证设在 1到Ｎ段的一系列奇数中有一素数Ｐ1 ,奇数标号为ｊ。如果在Ｎ到 2Ｎ段接近 2Ｎ处有一素数Ｐ2 ,依双奇数相加原则 ,如 (之四 )图 1 ,将Ｎ逐次增加 ,Ｐ2 将产生向Ｎ或Ｎ 1的方向移。在移位过程中对 1到Ｎ中的素数或合数逻辑值从小到大逐一扫描。当扫描到某一 2Ｎ时 ,Ｐ2 和Ｐ1 必然上下相对 ,其时 ,Ｐ1 =2ｊ - 1 ,Ｐ2 的奇数标号为Ｎ-ｊ 1 ,其绝对值为Ｐ2 =2 (Ｎ-ｊ 1 ) - 1 ,2Ｎ=Ｐ1 Ｐ2 ,为两素数相加即“1 1” ,这就是单点验证的理论依据。对于同一个 2Ｎ ,有时可能多次出现这一情况。点验可以求出每个 2Ｎ中“1 1…     

Toughening of MoSi2 with a ductile (niobium) reinforcement

The effect of interfacial reactions and Y₂O₃ coatings on toughening of MoSi₂ by ductile phase Nb reinforcements has been investigated. In the absence of coating the interfacial reaction layer exhibits parabolic growth with Mo₅Si₃, (Mo, Nb)₅Si₃, (Nb, Mo)₅Si₃ and Nb₅Si₃ phases forming. In precracked laminates subjected to tensile loads the ductile phase deformation is partially constrained, with debonding occurring within the interfacial reaction zone. Dense Y₂O₃ coating inhibits interdiffusion and results in more extensive debonding. In either case, significant toughening is expected with measured work of rupture values χ ≈ 5.7 to 6.3. Bulk composite MoSi₂ reinforced with 20 vol.% Nb particles subjected to a chevron-notched three point flexure test had a work of rupture almost five times larger than the unreinforced MoSi₂ matrix.     

Tribological properties of aluminum alloy matrix TiB2 composite prepared by in situ processing

An investigation of the wear behavior, in lubricated sliding and rolling of in situ prepared TiB₂ particle-reinforced 2024 T4 Al alloy matrix composites against 52100 steel and hardened pearlitic nodular cast iron, respectively, was undertaken. In sliding contact, the 10 vol pct 0.3-μm TiB₂-metal matrix composite (MMC) showed slightly less wear than the 10 vol pct 1.3-μm TiB₂-MMC. Transmission electron microscopy of cross sections, taken normal to the wear track and parallel to the sliding direction, revealed that the TiB₂ particles on the wear track were polished and particle pullout was largely absent. This was attributed to the strong interfacial bonding between the Al-alloy matrix and the TiB₂ reinforcing phase. The TiB₂ particles on the wear track inhibited spalling. Subsurface damage of the MMC did not occur. The wear of the steel mating surfaces worn against the TiB₂-MMCs was minor and caused by the cutting action of the TiB₂ particles that resided on the MMC wear track. In rolling contact, the 0.3-μm-size TiB₂-MMC showed 5 times higher weight loss than the 1.3-μm TiB₂-MMC for the same content of reinforcement, but the weight loss of the cast iron mating surface was less for the former. For the smaller particle size, the wear of 5 and 10 vol pct TiB₂-MMCs was the same. A high density of surface cracks was present on the wear track of the 0.3-μm TiB₂-MMC but not on the 1.3-μm MMC. The significance of strong particle/matrix interfacial bonding and particle size effect on the wear behavior of ceramic particulate-reinforced MMCs in lubricated sliding and rolling wear is discussed.     

配副体积比对铸铁干摩擦学特性的影响

金属干摩擦副双方的相对体积比影响摩擦热在干摩擦学系统中的分配,从而影响材料的干摩擦磨损性能,在铸铁／４０Ｃｒ钢摩擦副和铸铁闸瓦的实际装车运行试验中,均发现随着铸铁材料的磨损,其干摩擦磨损性能有不同程度的降低。蠕墨铸铁比灰铸铁具有理钕的干摩擦学稳定性。     

Mo含量对TiC基金属陶瓷材料力学性能影响研究

通过对用传统粉末冶金方法制取的4种成分各异的硬质合金试样进行强度、硬度测试以及XRD物相分析、SEM扫描电镜分析,研究Mo对TiC基硬质合金组织结构和力学性能的影响。实验结果表明:添加Mo后,(Ti1-xMox)C基金属陶瓷出现了类似TiC基金属陶瓷芯壳结构,其芯部为(Ti1-xMox)C,壳部为黏结相Co,这一点在XRD物相分析中得到证实;从SEM扫描可以看出,(Ti1-xMox)C基金属陶瓷的显微组织较细,断口较光滑,晶界较为明显,为典型的穿晶断裂;随着Mo元素的增加,(Ti1-xMox)C基金属陶瓷材料抗弯强度先降后增,最高为104 MPa;黏结剂Co的加入在一定程度上增加了材料的力学性能。     

Nb2O5掺杂对PZN-PZT压电陶瓷微观结构和电性能的影响

研究了施主掺杂离子Nb^5＋对Pb（Zn1/3Nb2/3）0.2Ti0.4Zr0.4O3 （PZN-PZT） 压电陶瓷微观结构和电性能的影响. Nb2O5加入量为0.0%～1.0%, 样品制备采用钶铁矿前驱体方法. 通过扫描电镜（SEM）和X射线衍射（XRD）分析, 确定了Nb2O5在钙钛矿主晶格中的固溶限度为0.5%左右. 少量Nb2O5能够抑制晶粒生长, 并导致四方相向三方相转变和晶体四方度的降低;而过量Nb2O5对晶粒尺寸、相转变和晶格畸变没有显著影响. 材料的电性能随Nb2O5加入量的增加而呈现极值型变化, 最优电性能在固溶限度处.     

超音速火焰喷涂TiB2 -Co涂层组织性能研究

采用机械合金化技术制备TiB2 -Co金属陶瓷复合粉末,通过超音速火焰喷涂技术制备TiB2 -Co金属陶瓷涂层.对TiB2 -Co金属陶瓷涂层的显微结构、硬度、耐磨损性能及磨损损机制进行研究。研究结果表明,涂层表面存在完全熔化区和部分熔化区;涂层呈典型的叠层状结构,与基材结合良好;涂层的硬度明显高于基体金属,是基体金属的4.5倍;磨损失重量仅为基体金属的磨损失重量的1/4;涂层磨损试样表面存在空穴和犁沟,其磨损机制主要为粘着磨损和磨粒磨损。     

MoSi2-Mo5 Si3复合材料的低温氧化研究

通过热重量分析、X射线衍射仪描电镜研究了MoSi2-Mo5Si3复合材料的低温氧化行为,指出材料低温氧化时,随Mo5Si量增多,材料氧化加剧,当Mo5Si3含量（质量分数）超过16％时发生“PEST”现象,由于MoO3晶须的大量存在,所形成的SiO2不能均匀连续地分布于材料表面,从而加剧了氧化。     

添加剂对钢铁发蓝处理工艺和发蓝膜性能的影响

在发蓝液基本配方的基础上,通过试验,研究了添加剂亚铁氰化钾与添加剂重铬酸钾对发蓝膜的影响,确定了最优的添加剂比例:重铬酸钾(0~0.01 g/l),亚铁氰化钾(0~0.1 g/l)。通过硫酸铜点滴试验、电化学极化曲线、循环伏安曲线、氯化钠溶液浸泡等多种方法表征了发蓝膜的性质,对钢铁制件表面处理起到很好的指导作用。     

Influence of SiO2 Addition on the Properties of Al2O3‐CaO‐CaF2 Slag

The Al₂O₃‐CaO‐CaF₂ slag system is used in making special quality steels by the electro‐slag re‐melting process (ESR). The purpose of our investigation was to analyse ESR slag that contained SiO₂. The slag samples with different SiO₂ fractions (0 ‐ 20 mass %) were examined by chemical analysis, differential thermal analysis, simultaneous thermal analysis, X‐ray diffraction, electron microscopy and wetting angle measurement. With addition of SiO₂ the polymerization of slags was increased due to the formation of new silicate complex compounds that influenced their melting points and wetting angles.     

MoSi2球磨工艺的探讨

通过Ｘ射线衍射手段测定了Ｍｏ和Ｓｉ粉在球磨过程中相的变化,讨论了不同球料比和球磨介质对机械合金化方法合成ＭｏＳｉ２相的影响。结果表明：采用质量较大的硬质合金介质且球料比为２０：１的工艺较为适宜。