添加TiC对WC-Co基硬质合金组织和力学性能的影响

采用粉末冶金工艺制备了不同TiC含量的WC-Ti-Co硬质合金。测定了常温力学性能,并采用XRD、SEM和EDS等方法分析了材料的相结构、组织形貌。试验结果表明,添加少量细晶粒TiC可以细化硬质合金的显微组织,提高其相对密度和硬度,但降低合金的断裂韧度。当TiC添加量为1.2%时,材料的综合力学性能最佳。     

TiC含量对Ta-2.5W合金组织和力学性能的影响

采用放电等离子体烧结法(SPS)制备了不同含量TiC颗粒的Ta-2.5W合金,利用光学显微镜、扫描电镜、显微硬度仪和拉伸试验等研究了 TiC含量对Ta-2.5W合金组织和性能的影响.结果表明:添加TiC可以细化合金的晶粒尺寸,TiC添加量为0.3 mass％时,合金的晶粒尺寸最小,硬度和强度均达到最大值.分布在晶界的TiC对晶界起钉扎作用是细化合金晶粒并提高其性能的主要原因.     

硬质合金复合刀具的制备及性能研究

采用热压烧结法制备了不同SiC晶须含量的硬质合金复合刀具,研究了不同SiC晶须含量对材料密度、硬度、孔隙度、断裂韧性和断口形貌的影响。结果表明,SiC晶须含量的增加会使得硬质合金复合刀具密度呈现逐渐降低的趋势;当SiC晶须含量为0.4%时,复合刀具可以取得硬度和断裂韧性的最大值;添加SiC晶须的复合刀具中的晶须拔出和晶须桥接机制可以有效提高复合刀具的强塑性。     

TiC含量对TC4合金激光熔覆层组织和性能的影响

采用激光熔覆工艺在TC4钛合金基体表面制备了添加不同质量分数(0%、2%、4%、6%)TiC的Ni60A复合熔覆层,通过光学显微镜、显微硬度计、X射线衍射仪、摩擦磨损机分析了不同TiC含量对熔覆层组织及性能的影响。结果表明:未添加TiC的熔覆层组织以树枝晶为主,添加TiC后出现了花瓣状物相;XRD分析发现熔覆层中出现了AlCCr₂、Al_0.24B_0.01Ni_0.75等硬质增强相,这些能够显著提高熔覆层的硬度。显微硬度及摩擦磨损试验结果表明,添加TiC的熔覆层平均硬度均较基体硬度有大幅提高,摩擦因数显著降低,且随TiC含量的增加,熔覆层硬度先增加后降低,摩擦因数先降低后增加,4%TiC熔覆层的硬度最大,相比基体提高了213.3%,摩擦因数最小,为0.309 774。     

Mo含量对TiC基金属陶瓷 组织和力学性能的影响

采用粉末冶金工艺制备了6组不同Ni、Mo添加量的金属陶瓷材料.通过扫描电镜观察组织结构、断口形貌及裂纹扩展,用三点弯曲法测试抗弯强度,用洛氏硬度计测得试样硬度.试验结果表明,添加Mo后,TiC基金属陶瓷呈现出典型的芯壳结构,组织细化明显.当TiC含量为70%、Ni∶Mo=2 ∶ 1时,材料的抗弯强度、硬度与断裂韧性综合...     

TiC对CuW触头材料组织与性能的影响

采用粉末冶金-熔渗法制备了不同TiC添加量的CuW合金。研究了添加TiC对CuW材料静态性能、真空电击穿性能及显微组织的影响。结果表明：TiC的添加量在0～1．2％（质量分数，下同）时，随着添加量的增加，合金的硬度逐渐升高，而电导率变化不大；当添加量在1．2％～2．0％范围内时，硬度和电导率则大幅下降。添加TiC相提高了CuW材料的耐电压强度，降低了截流值。对真空电击穿后的表面组织形貌分析发现，由于TiC相在钨骨架上的钉扎作用，铜液的飞溅较小；电击穿发生在Cu／TiC相界面上，且击穿坑较小。     

SiC晶须强韧化MoSi2复合材料的金相分析

热压合成制备MoSi2、SiCw+MoSi2材料.显微硬度测试和金相显微观察表明SiC晶须的加入可使MoSi2基复合材料晶粒细化、裂纹扩展受阻、显微硬度和断裂韧度提高;MoSi2基复合材料中SiC晶须偏聚和孔隙率过高以及不均匀分布,会导致材料晶粒大小不等,降低材料的强韧化效果.     

TiC对铁基合金喷焊层组织与性能影响

目的研究不同TiC添加量对铁基合金喷焊层组织与性能的影响。方法采用等离子喷焊技术在Q235表面制备了铁基合金喷焊层,借助X射线衍射分析、金相显微镜、显微硬度计以及磨粒磨损试验设备,分别对喷焊层的物相、显微组织、显微硬度、耐磨性能进行测试。结果未添加TiC的喷焊层主要由马氏体、奥氏体、(Fe,Cr)_7C_3、(Fe,Ni)固溶体等物相组成,加入不同含量的TiC后,出现了TiC、TiB_2等新物相,但各试样的衍射强度均存在相应程度的降低,某些区域的衍射峰甚至消失。随着TiC含量的增加,喷焊层的硬度和耐磨性增加,但硬度和耐磨性能在TiC添加量达到一定程度(w_(TiC)3.0%)时反而降低。当TiC添加量为3%时,喷焊层的组织致密,晶粒细化,TiC弥散分布,其颗粒对喷焊层组织产生了弥散强化和细晶强化作用;显微硬度可达843HV_(0.5),较未添加TiC喷焊层提高了约300HV_(0.5),其相对耐磨性较Q235钢提高了约12倍,显微硬度与耐磨性得到显著提高。结论添加适量的TiC颗粒,可使金属基体与硬质相达到良好匹配,从而确保了喷焊层的高硬度和良好的耐磨性能。     

TC4钛合金表面激光熔覆掺Y2O3复合涂层的显微组织和性能

目的提高钛合金表面的耐磨性能。方法在TiB_2:TiC=1:3的粉末配比下,添加不同质量分数Y_2O_3稀土氧化物,制备成膏状混合粉末。采用5 k W横流CO_2激光器,在TC4钛合金表面激光熔覆掺Y_2O_3的TiB_2和TiC粉末,制备耐磨性复合涂层。通过扫描电子显微镜(SEM)、X射线能谱仪(EDS)、X射线衍射仪(XRD)对激光熔覆层的微观形貌和组织成分进行了分析;用显微维氏硬度计对熔覆层的显微硬度进行了测量;用万能摩擦磨损试验机对熔覆层的耐磨性能进行了测试。结果添加4%Y_2O_3后,熔覆层中部组织明显细化,结合区由致密组织结构转变为晶须网状结构;熔覆层的最高显微硬度为1404.6HV0.2,是基体的3.7倍;熔覆层的磨损量减少了66.67%,且其摩擦系数有明显的降低。结论添加4%Y_2O_3对TC4钛合金表面激光熔覆TiB/TiC复合熔覆层耐磨性能有显著的提高。     

SiC含量对近β钛合金显微组织及力学性能的影响

通过真空非自耗熔炼工艺制备了不同SiCp添加量(0wt.%、0.1wt.%、0.4wt.%、1.wt.%)的近β钛合金。采用X射线衍射仪(XRD)、扫描电镜(SEM)、维氏显微硬度计和万能材料试验机,系统研究了SiCp添加量对近β钛合金显微组织及力学性能的影响规律。研究结果表明,不同SiCp添加量的近β钛合金主要由α-Ti、β-Ti和TiC所组成。近β钛合金的初生β晶粒尺寸取决于SiCp的添加量,SiCp添加量由0%增加到1wt.%时,近β钛合金初生β晶粒尺寸由639μm降低至323μm。由于受细晶强化、TiC承载强化以及Si的固溶强化的影响,随着SiCp添加量的增加,近β钛合金的显微硬度、压缩强度有显著提高,而压缩率却明显降低。     

Effect of TiC whisker addition on properties of YG10F alloy

The cemented carbide material （YG10F） with different additions of TiC whisker （0%, 0.3%, 0.6%, mass fraction） was prepared by different techniques. The effect of TiC whisker addition on the density, microhardness and toughness of the experimental material was investigated. The results indicate that after the wet-milling for 8 h and sintering in vacuum at 1 440 ℃, the toughness of YG10F is remarkably improved and meanwhile higher microhardness is obtained by 0.3% TiC whisker addition. Preliminary analysis suggests that the main toughening mechanism of TiC whisker in YG10F is whisker pull-out and bridging phenomena.     

Preparation,mechanical properties and microstructure of TiB2 based ceramic cutting tool material toughened by TiC whisker

TiC whiskers were synthesized by carbothermal reduction process. By using these whiskers as the toughening phase, a novel TiB₂ based ceramic cutting tool material was prepared. Due to that the thermal expansion coefficient of TiC is close to that of TiB₂, the addition of no more than 30 vol% TiC whisker not only has little adverse effect on the density and flexure strength of the composite, but also can refine the grains, reduce the defects and improve the grain strength. As a result, both the fracture toughness and flexure strength of the TiB₂ based ceramic composite can be significantly improved. Appropriate sintering temperature and holding time can reduce defects, improve the strength of grains and grain boundaries and enhance the toughening effect of TiC whiskers. Experimental results showed that when the whisker content was 30 vol%, the sintering temperature was 1700 °C and the holding time was 30 min, the flexure strength, fracture toughness and Vickers hardness of the TiB₂ based ceramic cutting tool material was 860 MPa, 7.9 MPa·m^1/2 and 22.6GPa, respectively.     

Microstructure of reactive synthesis TiC/Cr18Ni8 stainless steel bonded carbides

TiC/Cr18Ni8 steel bonded carbides were synthesized by vacuum sintering with mixed powders of iron, ferrotitanium, ferrochromium, colloidal graphite and nickel as raw materials. The microstructure and microhardness of the steel bonded carbides were analyzed by scanning electron microscope (SEM),X-ray diffraction (XRD) and Rockwell hardometer. Results show that the phases of steel bonded carbides mainly consist of TiC and Fe-Cr-Ni solid solution. The synthesized TiC particles are fine. Most of them are not more than 1 μm With the increase of sintering temperature, the porosity of TiC/Cr18Ni8 steel bonded carbides decreases and the density and hardness increase, but the size of TiC panicles slightly increases. Under the same sintering conditions, the density and hardness of steel bonded carbides with C/Ti atomic ratio 0.9 are higher than those with C/Ti atomic ratio 1.0.The TiC particles with C/Ti atomic ratio 0.9 are much finer and more homogeneous.     

TiC生成方式对激光熔覆镍基涂层组织和性能的影响

分别以TiC粉和Ti+C粉为原料,采用外加法和原位法制备了TiC/Ni激光熔覆涂层,分析了TiC生成方式对涂层物相组成、微观组织、硬度和磨损性能的影响。结果表明,涂层的物相组成不受生成方式的影响;但Ti+C质量分数高于30%时,原位法涂层无法成型,而外加法可获得40%TiC的涂层。外加法涂层中TiC以原料TiC为主,少量溶解析出的结晶TiC;而原位法涂层中TiC全部为结晶析出,分布更加均匀,颗粒细小,枝晶数量增多。原位法涂层的平均硬度和耐磨性均优于相同TiC含量的外加法涂层;涂层中TiC含量(质量分数)由20%增至30%时,涂层硬度升高,耐磨性下降,生成方式引起的磨损性能差异由5%降至0.6%。     

Laser cladding of Ti-6Al-4V alloy with TiC and TiC+NiCrBSi powders

Laser cladding of Ti-6Al-4V alloy with TiC and TiC+NiCrBSi powders was carried out, and microstructure, as well as microhardness profile, in the clad layers was examined. The results showed that, in the TiC clad layer, TiC was melted and solidified to form dendrites in the clad zone, and dissolved into the melted Ti-alloy substrate and precipitated to form well-developed dendrites in the dilution zone. With increasing specific laser energy, the dilution effect of the Ti-alloy substrate was enhanced, and the microhardness decreased in both the clad and the dilution zones. In the TiC+NiCrBSi laser clad layers, TiC particles dissolved into the melted Ni-based alloy (binder material) in the clad zone. With increasing specific laser energy, the degree of solution of TiC particles was increased. During cooling, fine spherical particles and dendrites of TiC precipitated from the Ni-based alloy. When the TiC volume fraction increased to more than 50%, clustering of TiC particles was observed in the clad zone. The clustering of TiC particles resulted in a decrease in the homogeneity of the microstructure and microhardness distribution in the clad zone. The dilution zone of the TiC+NiCrBSi clad layers is a mutually melted region of the Ni-based alloy and titanium-alloy substrate and presents a microstructure of dendrites.     

Nanocrystalline FeAl matrix composites reinforced with TiC obtained by hot-pressing consolidation of mechanically alloyed powders

Bulk FeAl matrix nanocomposites reinforced with 50%, 30% and 10% of TiC were produced by hot-pressing consolidation of mechanically alloyed nanocrystalline Fe(Al)–TiC composite powders containing different amounts of reinforcement. The powders were compacted at 1000 °C under a pressure of 7.7 GPa. Structural investigations of the consolidated materials revealed that transformation of the Fe(Al) solid solution into FeAl intermetallic had occurred during sintering and that both the matrix and the reinforcement remained nanocrystalline, with the mean crystallite size of about 20 nm. We infer that applying of a high pressure hinders grain growth at elevated temperature. The microhardness of the produced materials is relatively high, ranging between 1363 and 1608 HV0.2, depending on the amount of TiC. The density of the obtained bulk materials is very close to 100% of the “ideal” value and the open porosity is zero. These results as well as structural investigations show that the quality of compaction with preserving of the nanometric grain size of the composite constituents is satisfactory.     

Ti(C,N)基金属陶瓷制备工艺研究

实验采用日本新金属公司的TiC0.7N0.3,TiC0.5N0.5两种原料粉末,比较在不同制备工艺条件下,Ti(C,N)基金属陶瓷材料的力学性能。结果表明,原料、湿磨工艺、烧结工艺、烧结后的低压热等静压显著影响合金的力学性能及金相组织。     

Mechanical properties evaluation of hot-pressed Si3N4–SiC(w) composites

Silicon nitride based ceramic composites have been prepared using an alternative development route, aiming to reach properties for structural applications. The prepared compositions were silicon nitride based matrix with aluminum nitride and yttrium oxide, as sintering aids, reinforced with silicon carbide whiskers. The powders were grounded/homogenized directly as received. Samples were obtained by uniaxial hot-pressing and, physical (specific mass, X-ray diffraction and microstructural analysis) and mechanical (microhardness, fracture toughness and flexural strength) properties were determined. The resulting high fracture toughness values were related to crack deflection and crack bridging toughening mechanisms, observed by SEM.     

自生TiC_w－AlN_p／Al复合材料中TiC_w相的形成和分布

用固－气－液三态反应方法和合适的冷却条件制备了自生ＴｉＣｗ－ＡｌＮｐ／Ａｌ复合材料。讨论了ＴｉＣｗ晶须的形成机制和强化特点；并用电子显微镜观察了基体被部分腐蚀掉的ＴｉＣｗ－ＡｌＮｐ／Ａｌ复合材料中ＴｉＣｗ的立体形貌和空间分布特征。     

Electrically conductive ZTA–TiC ceramics: Influence of TiC particle size on material properties and electrical discharge machining

Processing of highly abrasive materials via powder injection molding or extrusion requires mold materials with high wear resistance to increase the durability of the tools and to sustain a high quality of the manufactured products. High performance ceramics which exhibit high hardness, bending strength and toughness show the perfect combination of properties for these applications. However they also have the usual drawback that they cannot be economically customized in complex shapes and low quantities, as they are required for tool and mold design. Recent material development enabled EDM of electrically conductive oxide ceramics, the most widespread machining process for machining of hard materials, as an alternative to conventional ceramic manufacturing and hard machining technologies.This study focuses on the influence of TiC particle sizes on material properties and EDM machinability of ZTA–TiC ceramics with 24 vol.% TiC, 17 vol.% ZrO₂ and 59 vol.% Al₂O₃. Fracture toughness, bending strength and electrical conductivity were analyzed for samples produced from TiC powders with particle sizes varying from 0.43 μm to 2.54 μm. Surface integrity of wire cut samples and feed rate during machining were investigated. It was shown that reducing the size of electrical conductive grains strongly increases the electrical conductivity and slightly decreases mechanical properties. Therefore also the machining characteristics are influenced by TiC grain size. The feed rate increases with decreasing particle size to a maximum at d₅₀ = 1–1.3 μm. Reduction of TiC particle size also leads to significantly decreasing surface roughness after the main cut. Additionally the necessary number of trimming steps to achieve a distinct surface roughness is also minimized for low particle sizes.