Ti(C,N)基金属陶瓷成分对抗热震性能的影响

制备了不同碳氮比Ti(C,N)固溶体和分别加入NbC、TaC、VC、Cr_(3)C_(2)的Ti(C,N)基金属陶瓷,采用水淬冷热震方法研究了不同成分对Ti(C,N)基金属陶瓷抗热震性能的影响。结果表明:金属陶瓷在热冲击过程中,陶瓷相在热应力的作用下会发生开裂现象,在裂纹扩展路径上产生的微裂纹能促进裂纹扩展;在不同碳氮比的Ti(C_(x),N_(y))固溶体金属陶瓷中,碳氮比7/3的Ti(C_(0.7),N_(0.3))金属陶瓷的抗热震性能最好,本文研究中其热震临界温度为240℃;在添加的四种碳化物(NbC、TaC、VC和Cr_(3)C_(2))中,NbC和TaC能显著提升金属陶瓷的抗热震性,且TaC更优于NbC,而VC和Cr_(3)C_(2)的加入不利于改善金属陶瓷抗热冲击性能。

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 Powder Particle Size on the Properties and Microstructure of Ti(C,N)-Based Cermet

The influence of raw powder particle size on the properties and microstructures of Ti (C, N)-based cermets has been studied. The conclusions are as follows: The microstructures of cermets were composed of two kinds of grains, the one with black cores surrounded by obvious rim structures, and the other whose cores were white with unconspicuous rim structures and adhesive phase. In the cermet made from fine powders, the amount of grains with white cores was much more than that in cermet made from coarse powders. In addition, their properties were also much better.

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 micmstructure and properties of Ti（C,N）-based nano cermets was investigated. The results showed that there existed black-core grayish-rim strucmre 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 in- creased, 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.

Microstructure and shear strength of the brazed joint of Ti(C,N)-based cermet to steel

Firm joins were obtained between Ti（C,N）-based cermet and steel with Ag-Cu-Zn-Ni filler metal by vacuum brazing. The effects of technological parameters such as brazing temperature, holding time, and filler thickness on the shear strength of the joints were investigated. The microstructure of welded area and the reaction products of the filler metal were examined by scanning electron microscopy （SEM）, metallographic microscope （OM）, energy-dispersive X-ray analysis （EDS）, and X-ray diffraction （XRD）. The brazing temperature of 870℃, holding time of 15 min, and filler thickness of 0.4 mm are a set of optimum technological parameters, under which the maximum shear strength of the joints, 176.5 MPa, is achieved. The results of microstructure show that the wettability of the filler metal on Ti（C,N）-based cermet and steel is well. A mutual solution layer and a diffusion layer exist between the welding base materials and the filler metal.

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.

Comparative study of the fabrication of ultrafine Ti(C,N)-based cermets by spark plasma sintering and conventional vacuum sintering

Spark plasma sintering (SPS) and conventional vacuum sintering (VS) wereemployed to fabricate ultrafine Ti(C,N)-based cermets. The shrinkage behavior, microstracture, andporosity and mechanical properties of the samples fabricated by SPS were compared with those of thesamples sintered by VS using optical microscopy, scanning electron microscopy, universal testingmachine, and rockwell tester. The results are as follows: (1) The shrinkage process occurred mainlyin the range of 1000-1300 deg C during the VS process, and only a 0.2 percent linear shrinkage ratioappeared below 800 deg C; during the SPS process, a 60 percent dimensional change occurred below800 deg C as a result of pressure action. (2) By utilizing the SPS technique, it is difficult forobtaining fully dense Ti(C,N)-based cermets. Due to the much existence of pores and un-combinedcarbon, the mechanical properties of the sintered samples by SPS are inferior to sintered ones byVS. (3) grain size of the samples sintered by SPS is still below 0.5 urn, but not by VS; because oflow sintering temperature, there are no typical core/rim structures formed in the sintered samplesby SPS1; the main microstructures of the sintered samples by SPS2 are a white core/grey shellstructure, whereas by VS show a typical black core/grey shell structure.

Spark Plasma Sintering Properties of Ultrafine Ti(C,N)-based Cermet

Ultrafine Ti(C,N)-based cermet was sintered by SPS from 1050℃ to 1450℃ and its sintering properties,such as porosity,mechanical properties and phase transformation,were investigated by optical microscopy (OM),scanning electron microscopy (SEM),X-ray diffraction (XRD),and differential scanning calorimeter (DSC).It is found that the spark plasma sintering properties of Ti(C,N)-based cermet differ from those of conventional vacuum sintering.The liquid phase appearance is at least lower by 150℃ than that in vacuum sintering.The porosity decreases sharply below 1 200℃ and reaches minimum at 1 200℃,and afterwards it almost keeps invariable and no longer increases.SPS remarkably accelerates the phase transformation of Ti(C,N)-based cermet and it has a powerful ability to remove oxides in Ti(C,N)-based cermets.Above 1 350℃,denitrification occurred.Fresh graphite phase formed above 1 430℃.Both the porosity and graphite are responsible for the poor TRS.

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 mechanical properties of Ti(C, N)-based cermets with different molybdenum contents

The microstructure and mechanical properties of Ti(C, N)-based cermets with different content Mo were studied. Different Mo contents were added into Ti(C, N)-based cermets. Effect of sintering temperature on mechanical properties of the cermets was also investigated. Specimens were fabricated by conventional powder metallurgy techniques and vacuum sintered at different temperatures. The microstructure and the fracture morphology were investigated using scanning electron microscope. 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%. The mechanical properties are the best when the content of Mo is 8% and the sintering temperature is 1450℃.

Effect of sintering parameters on powder injection molded Ti(C, N)-based cermets

Effect of two-stage sintering parameters such as heating rate, top sintering temperature and holding time, sintering temperature and holding time at the second stage on relative density, transverse rupture strength(TRS) and microstructures of powder injection molded Ti(C, N)-based cermets were investigated, by means of Archimedes’s method, three-point bending test and micrographic analysis. The results show that the optimum sintering cycle for powder injection molded Ti(C, N)-based cermets comprises rapid heating (10℃/min) at low temperatures, slow heating (5℃/min) at intermediate temperatures, holding at the highest sintering temperature (1420℃) for a short time (10min), and holding at the second stage (1360℃) for a longer time (6h) to avoid grain coarsening, and that its TRS reaches 624MPa, and there are little pores in their microstructures.

Preparation of ultrafine Ti (C, N)-based cermet using oxygen-rich powders

The availability using oxygen-rich powders to prepare ultrafine Ti(C,N)-based cermets was investigated. The deoxidation process, denitrification phenomenon and the effect of deoxidation on microstructure and mechanical properties of sintered samples were discussed, respectively. The results show that oxygen in the samples prepared even with high oxygen contained in starting powders can be almost completely cleaned away through suitable sintering process. The ultrafine oxygen-rich powders have a significant effect on microstructure, which promotes the formation of white core phase. A ultrafine Ti(C,N)-based cermet with mean particle size of 0. 30 μm, uniform microstructure and excellent mechanical properties is successfully prepared. It is also found that there exists severe denitrification phenomenon in the preparation process of ultrafine Ti(C,N)-based cermet.

Ti(C,N)基金属陶瓷复合材料的制备与性能研究

在现代材料科学领域,金属陶瓷复合材料因其独特的物理和化学性质,在航空航天、汽车制造、能源等领域得到了广泛的应用。其中,Ti(C,N)基金属陶瓷复合材料以其高强度、低密度和优异的耐腐蚀性能而备受关注。文章以实验研究的方式探究Ti(C,N)基金属陶瓷复合氮化硼材料的制备工艺及其性能,以期为各个应用领域的进一步发展提供理论依据。

核壳结构SiC@Ti(C,N)复合材料的制备及性能研究

目的 碳化物陶瓷材料因优异的力学性能在精加工和切削行业具有广阔的应用前景,制备特定结构的碳化物复合材料能够改善材料的综合性能。方法 通过化学法在SiC表面包覆纳米Ti(C,N),无压烧结制备了具有核壳结构的SiC@Ti(C,N)复合材料。采用XRD、SEM、TEM和EDS等方法,研究退火温度和原料配比对复合材料的成分组成和微观结构的影响。通过同步热分析(TG-DSC)比较单相和复合材料抗氧化性能差异。使用显微维氏硬度计和万能材料试验机测试材料力学性能的变化趋势及原因。构建核壳颗粒致密化模型,分析复合材料的致密化机制和增韧机理。结果 随着烧结温度的升高,其显微硬度先升高后降低。随着SiC比例的增大,其显微硬度、压缩强度和断裂韧性均先增大后减小。在1250℃下,制备的原料质量比为11:1的SiC@Ti(C,N)复合材料具有最大显微硬度、压缩强度和断裂韧性,分别为3 273HV、434 MPa、4.38MPa·m^(1/2)。结论 通过比较复合材料和单一碳化物材料的力学性能发现,具有核壳结构的SiC@Ti(C,N)复合材料综合性能得到提升。纳米Ti(C,N)填充复合材料孔隙并促进致密化烧结,从而提升了复合材料的强度;通过Ti(C,N)骨架的偏转裂纹实现增韧。

FEM simulation on residual stress distribution during diffusion bonding between Ti （ C, N） metallic ceramic/interlayer/40Cr steel

Based on ANSYS FEM software, the distribution of residual stress in the diffusion bonding joints between Ti（ C,N） metallic ceramic/interlayer/4OCr steel was calculated and experimentally ver^ed. The results showed that the trend on the distribution of residual stress field in the joints was not changed with the use of interlayer. The maximum residual stress was always located in metallic ceramic with area ranging from 1 mm to 4 mm to the interlayer. The maximum residual stress in the joints was also affected by diffusion temperature. The satellite pulse current during the initial stage on diffusion bonding can promote the formation of liquid film at the interface, by which diffusion temperature and loading pressure can be greatly decreased. The crack initiation was easily produced at the corner of Ti （ C, N） metallic ceramic close to the interlayer. If a higher residual stress produced in the joints, the crack was propagated into the whole ceramic.

Ti(C,N)基金属陶瓷的研究

研究了合金组成及其含量、烧结工艺、热等静压等对Ｔｉ（Ｃ，Ｎ）基金属陶瓷性能的影响。氮的加入形态、Ｎ／Ｃ、钼、镍、碳对合金性能都有影响。其中，Ｎ／Ｃ比值影响粘结相、硬质相的晶格常数及钼在粘结相和ＳＳ相的溶解量。当ＴｉＮ质量分数增加到２６％或镍质量分数增加到２５％时产生Ｎｉ３Ｍｏ相，缺碳则出现Ｎｉ３Ｔｉ相。真空烧结温度超过１４５０℃，ＴｉＮ分解，造成合金收缩率下降。热等静压处理后，抗弯强度提高了７０％以上，相对密度达到９９６％以上，硬度值（ＨＲＡ）提高了０９～１７。

Ti(C,N)/40Cr钎焊接头残余应力数值计算

使用有限元法模拟计算了Cu箔、Mo箔对缓解Ti(C,N)/40Cr钎焊接头残余应力的效果。结果表明,无缓冲层直接钎焊,在Ti(C,N)金属陶瓷外侧靠近钎缝的狭小区域内产生较高的拉伸残余应力,其峰值达到268 MPa;使用屈服极限低的Cu箔,接头最大残余拉应力下降到98 MPa,缓解应力效果显著,但最大残余拉应力所处区域与无缓冲层相比没有明显变化;使用线膨胀系数小的Mo箔,应力峰值出现在Mo箔中,同时缓解应力效果不如Cu箔;无论使用Cu箔还是Mo箔,最佳厚度约为0.8 mm左右,大于或小于该厚度值,应力得不到有效释放。

Ti(C,N)基金属陶瓷刀片的性能

阐述了两种Ｔｉ（Ｃ，Ｎ）基金属陶瓷刀具的研制过程。通过对材料的力学性能、耐磨性能、抗冲击性能和显微结构的比较试验，研制成功一种具有应用价值的Ｔｉ（Ｃ，Ｎ）硬质刀具。

SiC晶须和Ti(C,N)颗粒协同增韧Al_2O_3陶瓷刀具的研究

采用热压工艺烧结制备了SiCW Ti(C ,N) Al2 O3(Y2 O3)陶瓷刀具复合材料。研究了不同烧结温度(16 0 0～ 175 0℃ )下 ,材料的致密度和力学性能 (断裂韧性KIC ,维氏硬度HV和抗弯强度σf)随晶须含量 (10 %～4 0 % )的变化关系 ;探讨了SiC晶须和Ti(C ,N)颗粒对Al2 O3基体的协同增韧机理。同时与SiCW Al2 O3陶瓷及Ti(C ,N) Al2 O3陶瓷作对比研究。结果表明 :SiCW Ti(C ,N) Al2 O3(Y2 O3)陶瓷材料在 175 0℃ ,晶须含量为 2 0 %时获得最佳的综合力学性能 :KIC =7 11MPa m1 2 ,HV =2 1 16GPa ,σf=82 0MPa ;明显高于SiCW 含量为 2 0 %的SiCW Al2 O3陶瓷和不加晶须的Ti(C ,N) Al2 O3陶瓷。第三相Ti(C ,N)颗粒的加入与晶须一起产生明显的迭加增韧效果 ,而且对SiCW 的各种增韧机制起到了促进作用。

Ni和Ti的添加对Al_2O_3-Ti(C,N)复合材料性能的影响

研究了Ni和Ti的添加对真空热压烧结方法制备的Al2O3-Ti(C,N)陶瓷基复合材料的显微组织和力学性能的影响.发现添加Ni和Ti的复合材料主要由Al2O3、Ti(C,N)和Ni组成,没有发现存在金属Ti.Ti由于非常活泼,在热压烧结过程中可能与石墨模具产生的含C气氛反应生成TiC,或与高温下Ti(C,N)的少量分解产生的N2气氛反应生成TiN,这有利于减少复合材料中的气孔.适量添加Ni可通过液相烧结促进复合材料的致密化,提高复合材料的相对密度,并能通过产生裂纹偏转和裂纹桥联提高复合材料的断裂韧性.热压温度为1550℃、等摩尔比的Ni和Ti混合粉末添加量为5vol%时,Al2O3-Ti(C,N)-Ni-Ti复合材料的相对密度为99.6%,硬度为21GPa,抗弯强度为818MPa,断裂韧性为8.1 MPa.m1/2.