VC/Cr_3C_2对Ti(C,N)基金属陶瓷微观组织和力学性能的影响(英文)

研究VC/Cr3C2对Ti(C,N)基金属陶瓷微观组织和力学性能的影响。利用光学显微镜、X射线衍射仪和扫描电镜结合能谱仪研究微观组织。测试横向断裂强度、硬度和断裂韧性等力学性能。结果表明:微观组织中存在"黑芯-灰壳"和"白芯-灰壳"结构;由于添加VC/Cr3C2,硬质相晶粒变细,添加0.75VC/0.25Cr3C2的金属陶瓷晶粒细化最明显;黑芯随着VC添加量的增加而变细,壳随着Cr3C2添加量的减少而变厚;孔隙率随着VC/Cr3C2中VC的量增加而增大;横向断裂强度和硬度均升高,并且均在添加0.25VC/0.75Cr3C2时达到最大值;按适当的VC和Cr3C2添加量比例添加VC/Cr3C2可以有效地使断裂韧性升高,并在添加0.5VC/0.5Cr3C2时取得最大值。     

VC对纳米Ti(C,N)基金属陶瓷组织和性能的影响

研究了添加0～2.0%晶粒长大抑制剂VC对纳米Ti(C,N)基金属陶瓷组织和性能的影响。结果表明,VC的加入使金属陶瓷的晶粒得到细化,抗弯强度、硬度提高,断裂韧度下降。在VC添加量为1.0%时,该金属陶瓷的抗弯强度为1204.6 MPa,维氏硬度为14.5 GPa,其综合性能最高。     

Ti(C,N)_w/Ti(C,N)基金属陶瓷的组织与力学性能研究

采用Ti(C,N)晶须和颗粒复合粉末(Ti(C,N)w+Ti(C,N)p)制备Ti(C,N)w/Ti(C,N)基金属陶瓷。研究了复合粉末对金属陶瓷组织及性能的影响。结果表明,Ti(C,N)w的加入,金属陶瓷的各项力学性能都得到了提高。组织表现为环形相结构特征,与Ti(C,N)基金属陶瓷相比,双层环形相结构所占比例增大,且尺寸加厚。烧结组织中Ti(C,N)w的长径比大于临界长径比,在强化金属陶瓷方面起着重要的作用。环形相使Ti(C,N)w与基体界面结合紧密,增韧机制主要表现为裂纹桥联和裂纹偏转,拔出效应不明显。     

NbC含量对Ti(C,N)基金属陶瓷组织和力学性能的影响

研究了NbC含量对两种不同Ti(C,N)/TiC质量比金属陶瓷组织和性能的影响。结果表明:随着NbC含量的增长,环形相变得更加完整,粘接相分布越均匀。TiC和NbC含量的不同,影响了溶解和扩散,造成环形相与硬质相的体积分数和元素分布不同。力学性能测试表明,Ti(C,N)/TiC质量比为3︰2、w(NbC)=6%的试样的综合力学性能较好。     

碳纳米管添加量对Ti(C,N)基金属陶瓷组织和力学性能的影响

采用真空烧结工艺制备了Ti(C, N)基金属陶瓷,通过XRD、TEM和SEM等手段研究碳纳米管(CNTs)对金属陶瓷组织和性能的影响.结果表明:与未加碳纳米管的基体组织相比,添加CNTs的金属陶瓷组织中具有"白芯-灰壳"结构的小颗粒大大增加,金属陶瓷晶粒逐渐细化且分布均匀;当CNTs添加量(质量分数)为0.5%时,Ti(C, N)基金属陶瓷的硬度可达90.9HRA;金属陶瓷的抗弯强度比未加碳纳米管的试样提高14.1%,可达2 180.7 MPa,其强化机制主要为细晶强化;金属陶瓷的断裂韧性比未加碳纳米管的试样提高18.5%,可达14.7 MPa·m1/2,CNTs对金属陶瓷强韧化机制主要为桥联作用、拔出效应和裂纹偏转作用.     

N含量对超细Ti(C,N)基金属陶瓷显微组织和力学性能的影响

用扫描电子显微镜(SEM)、金相显微镜等观察手段研究了N含量对超细Ti(C,N)基金属陶瓷显微组织和力学性能的影响.结果表明N含量对超细Ti(C,N)基金属陶瓷显微组织和力学性能有显著的影响.随N含量增加,其晶粒尺寸细化,晶粒长大受到抑制,并且这种抑制作用非常显著.与此同时,组织中高的N含量也会导致烧结体中孔隙率增加,严重损害着横向断裂强度(TRS).高的N含量一方面能有效抑制晶粒长大,另一方面也促进N的分解.     

Ti(C,N)固溶体的N/C原子比对Ti(C,N)基金属陶瓷组织及力学性能的影响

本文以不同N/C原子比的Ti(C,N)固溶体为硬质相,通过真空烧结制备了Ti(C,N)基金属陶瓷。用三点弯曲法、洛氏硬度计、压痕法分别测得试样的抗弯强度、硬度、断裂韧性,并通过光学金相显微镜、XRD、SEM、EDS等手段研究了Ti(C,N)固溶体的N/C原子比对Ti(C,N)基金属陶瓷组织的影响规律。结果表明:在一定范围内随着N/C原子比的增大,Ti(C,N)固溶体在液相中溶解度下降,环形相的析出受到抑制,使得金属陶瓷的硬质相芯部逐渐细化且分散均匀,环形相厚度减薄。但Ti(C,N)固溶体的N/C原子比为6∶4及以上时,硬质相与液相之间的润湿性较差,使得金属陶瓷孔隙度增加,显微组织中开始出现亮白色的晶粒。随N/C原子比的增大,金属陶瓷的抗弯强度和硬度先增大后降低,断裂韧性逐渐降低。当Ti(C,N)固溶体的N/C原子比为5∶5时,金属陶瓷的综合力学性能最佳,其抗弯强度为2 429 MPa,硬度为92.2 HRA,断裂韧性为8.44 MPa·m~(1/2)。     

渗硼对Ti(C,N)基金属陶瓷组织和性能的影响

采用粉末冶金法制备了纳米改性Ti(C,N)基金属陶瓷,并用固体粉末法对其进行了渗硼处理。研究了渗硼处理对Ti(C,N)基金属陶瓷微观组织以及抗弯强度和硬度的影响。结果表明:渗硼处理使Ti(C,N)基金属陶瓷中生成了CoB、TiB2、MoB2和石墨相。金属陶瓷的渗硼层由硼化物层、扩散层和基体区组成,厚度为100～140μm。硼化物层主要由CoB组成,扩散层含有较多孔隙,基体区存在富硼的渗硼影响区,影响区具有与Ti(C,N)基金属陶瓷近似的微观组织,但金属相含量较少。渗硼处理使Ti(C,N)基金属陶瓷的抗弯强度降低,主要是由材料中产生的热应力、组织应力以及组织变化引起的。Ti(C,N)基金属陶瓷的表面硬度提高48.7%。在由渗硼层表面向内部100～140μm范围内,硬度呈下降趋势。     

Cr_3C_2对纳米Ti（C,N）基金属陶瓷组织和性能的影响

研究了Cr3C2含量对纳米Ti（C,N）基金属陶瓷组织和性能的影响。测定了抗弯强度、硬度和断裂韧度;进行了XRD相结构分析;用扫描电镜观察了组织结构与断口形貌。结果表明,Cr3C2添加量为1.5%时,材料的综合性能最好。     

Cr_3C_2对Ti(C，N)基金属陶瓷性能的影响

采用真空液相烧结法制备了添加微量TaC、NbC的(Ti,Ta,Nb)(C,N)-(Ni,Mo)- Cr_3C_2系Ti(C,N)基金属陶瓷。对添加不同质量Cr_3C_2材料的力学性能、断口形貌和高温氧化过程进行了研究。结果表明:随Cr_3C_2加入量的增加,材料的硬度呈增加趋势,抗氧化性能逐渐提高,但抗弯强度降低;Cr_3C_2加入量为12.5wt%时,材料的综合性能最佳,其高温氧化机制为外界氧离子通过氧化层向反应界面的扩散。     

Effect of VC addition on the microstructure and properties of Ti（C,N）-based nano cermets

In this paper, Ti(C,N)-based nano cermets were prepared by nano particles, and the effect of VC addition on the microstructure and properties of Ti(C,N)-based nano cermets was investigated. The results showed that there existed black-core grayish-rim structure as well as gray-core grayish-rim structure in VC-doped Ti(C,N)-based nano cermets. With the increase of VC addition, the number of gray cores increased, the lattice parameter of Ti(C,N) phase increased, the grain size decreased, the hardness and fracture toughness of Ti(C,N)-based nano cermets were enhanced, and nearly full densification could be achieved. However, excessive addition of VC to 1 wt% resulted in slight decrease in hardness and fracture toughness. Some deep dimples were found in the fracture surface of cermets with VC addition, which corresponded to ductile fracture.     

Effects of molybdenum on the microstructure and mechanical properties of Ti（C,N）-based cermets with low Ni

The effects of Mo on the microstructure and mechanical properties of Ti（C,N）-based cermets with low Ni have been studied systematically. Different contents of Mo （4-12 wt.%） were added into Tl（C,N）-based cermets. Specimens were fabricated by conventional powder metallurgy and vacuum sintered at temperatures of 1440, 1450, and 1460℃ individually. The microstructure and fracture morphology were investigated by scanning electron microscope, and the mechanical properties such as transverse strength and hardness were measured. The results show that the microstructure is uniform and the thickness of rim phase is moderate when the content of Mo is 8 wt.%; the mechanical properties of the specimens sintered at 1450℃ are better than those sintered at 1440 and 1460℃. The integrated properties of transverse strength and hardness are the best when the content of Mo is 8 wt.% and the sintering temperature is 1450℃.     

Effect of hot isostatic pressing nitrogen on the microstructure and properties of a Ti（C, N）-based cermet

The high-temperature, high-pressure hot isostatic pressing technology was used for depositing hard coatings on Ti（C, N）-based cermets. The rnicrostructure and properties of the sample were investigated using optical microscopy, scan- ning electron microscopy, X-ray diffraction, electron probe microanalysis, and microhardness tester. The results showed that the rich titanium and nitrogen in surface zone were induced by the heat treatment. The high nitrogen activity of the surface region was the driving force for outward transport of titanium and inward transport of tungsten in the cobalt binder. The toughness and hardness were improved and a hardness gradient was formed. It is the high-temperature, high-pressure N2 that enables closure of holes, thereby alleviating defects and prolonging tool life.     

Microstructure and cutting performance of Ti（C, N）-based cermets heat-treated in nitrogen

Ti（C, N）-based cermets were treated using hot isostatic pressing （HIP） at 1423 K in nitrogen. The microstructures compared with the as-sintered cermets were investigated using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray analysis, and electron microprobe analysis. It was found that high nitrogen activity in the surface zone resulted in the formation of gradient structure. Approximately 20-1am-deep, nitrogen-rich and titanium-rich hard surface zone was introduced by the heat treatment. The nitrogen activity was the driving force that caused the transportation of the atoms through the binder, titanium towards the surface, and tungsten and molybdenum inwards. In the surface zone, the particle size became fine, the inner rim disappeared, and the volume fraction of the outer rim and the binder phase considerably reduced. Small grains of TiN, WC, Mo2C, and nitrogen-rich carbonitlide phases formed in the surface zone during the heat treatment, improving the tlibological property of the heat-treated cermet.     

Ti(C,N)基金属陶瓷的芯-壳显微结构与性能研究

以TiC、TiN为原料,Ni、Co为粘结剂,WC、Mo2C、TaC、C、Cr3C2为添加剂,采用真空热压烧结工艺制备Ti(C,N)基金属陶瓷材料。借助于SEM、EDS和XRD分别分析其显微结构、组成和物相,并测试其性能。结果表明:按配方(质量分数,%):TiC:41.2,TiN:10,Ni:7,Co:7,Mo2C:12,WC:15,TaC:6,Cr2C3:0.8,C:1配料,在1450℃,30MPa热压制得的试样晶粒细小,具有完整的芯-壳显微结构。其主要性能为:相对密度99.12%,维氏硬度22.74GPa,断裂韧性10.1MPa·m1/2,抗弯强度1192.83MPa。     

Influence of preparation process on sintering behavior and mechanical properties of ultrafine grained Ti（C, N）-based cermets

The influences of forming and sintering processes on distortion, cracking as well as mechanical properties of sintered bodies of ultrafine grained Ti（C, N）-based cermets were investigated. The results show that lubricant is indispensable to fabrication of ultrafine Ti（C, N）-based cermets, however, with low binder content in powder mixture, the lubrication action of paraffin is attenuated. A appropriate level of 2% （mass fraction） paraffin is determined for a cermet with binder content of 36% （mass fraction）. It is also found that the influence of compaction pressure on distortion and cracking of sintered bodies presents a complex relationship. A relatively lower or higher compaction pressure, less than 100 MPa and more than 400 MPa respectively, favors uniform density distribution in green compact. The heating rate of sintering should be strictly controlled. Too fast heating rate results in enclosed pores to burst and forms large size pores in sintering body. A heating rate of 3 ℃/min is recommended.     

Cr_3C_2对纳米TiN改性Ti（C,N）基金属陶瓷组织和性能的影响

研究了添加0%～2.5%（质量分数）晶粒长大抑制剂Cr3C2对纳米TiN改性的Ti（C,N）基金属陶瓷组织和性能的影响。结果表明,添加Cr3C2后,Ti（C,N）基金属陶瓷的晶粒显著细化,抗弯强度也得到提高。Cr3C2添加量为1%时,抗弯强度达到最大值1407 MPa;添加适量Cr3C2可提高材料的硬度和断裂韧度,添加量为1.5%时,维氏硬度达到最大值15.8 GPa,添加量为1%时,断裂韧度达到最大值10.7 MPa.m1/2。     

二次颗粒尺寸和添加WC对双结构金属陶瓷组织和性能的影响

研究了二次颗粒尺寸和添加WC对双结构金属陶瓷组织和力学性能的影响,结果表明二次颗粒均匀地分布在基体中,随着添加WC含量的增加,组织中白芯灰壳结构和无芯结构增加。组织中发现了一种新的四层复合结构的硬质相。随着二次颗粒尺寸的增加,材料的断裂韧性提高,但抗弯曲度和硬度下降,而提高WC加入量,断裂韧性和抗弯曲度提高,但硬度有所下降。更高的断裂韧性主要归功于裂纹的分叉、桥接、偏转、微裂纹以及二次颗粒的拔出效应。     

WC含量对超细Ti(C,N)基金属陶瓷组织和性能的影响

采用真空烧结法制备超细Ti(C,N)基金属陶瓷,研究WC含量0wt%～20wt%对超细Ti(C,N)基金属陶瓷显微组织和力学性能的影响。通过SEM观察组织形貌发现,添加WC后金属陶瓷的组织出现了典型的芯壳结构,并且芯壳产生了明显细化,但当WC添加量超过15wt%时,环形相碳化物粗化、变脆。伴随着WC添加量,抗弯强度、硬度、断裂韧性均呈现先上升再下降的趋势。在WC添加量15wt%时,抗弯强度达到1262MPa,维氏硬度值达到16.3HV,金属陶瓷的综合力学性能达到最优。     

Effect of sintering on microstructures and properties of sub-micron Ti （C, N）-based cermets

The influence of different sintering processes, including vacuum sintering, vacuum sintering followed by HIP and sintering-HIP, on the microstructure and properties of sub-micron Ti(C,N) cermets with various binder contents was studied. Image analysis based on back-scattered electrons image observations was used to determine the morphologic and structural characteristics. Transverse rupture strength(TRS), hardness, fracture toughness were measured and TRS data were treated by Weibull statistics further. It is shown that a very significant improvement in TRS can be obtained by HIP or sintering-HIP treatment for the alloys with lower and middle binder content at the controlled cooling rate, but the effect is not obvious for the alloys with higher binder content. HIP is also helpful for improving the hardness of sub-micron Ti(C,N) cermets, however, but can lower the fracture toughness. The varia-tion of these properties was interpreted in terms of the difference in morphologic and structural characteristics.