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1.
Two series of Ti (C, N)-based cermets, one with TiC addition and the other with TiN addition, were fabricated by conventional powder metallurgy technique. The initial powder particle size of the main hard phase components (Ti (C, N), TiC and TiN) was nano/submicron-sized, in order to achieve an ultra-fine grade final microstructure. The TiC and TiN addition can improve the mechanical properties of Ti (C, N)-based cermets to some degree. Ultra-fine grade Ti (C, N)-based cermets present a typical core/rim (black core and grayish rim) as well as a new kind of bright core and grayish rim structure. The average metallic constituent of this bright core is determined to be 62 at% Ti, 25 at% Mo, and 13 at% W by SEM–EDX. The bright core structure is believed to be formed during the solid state sintering stage, as extremely small Ti (C, N)/TiC/TiN particles are completely consumed by surrounding large WC and Mo2C particles. Low carbon activity in the binder phase will result in the formation (Ni2Mo2W)Cx intermetallic phase, and the presence of this phase plays a very important role in determining the mechanical properties of TiN addition cermets. 相似文献
2.
《Ceramics International》2015,41(8):9259-9264
Ni–Mo–C/Ti(C,N) coated powders, namely Ni–Mo alloy and Mo2C coated Ti(C,N) composite powders, were synthesized by using a heterogeneous precipitation and thermal reduction method, then pressed and vacuum sintered to fabricate cermets. The chemical composition, microstructure and phases of the composite powders and the microstructure and properties of sintered cermets were experimentally investigated. The results show that a fine and uniform microstructure of (Ti,Mo)(C,N)-Ni cermets without the conventional core-rim structure is obtained. The phases formed during the preparation of the coated powders as well as the cermets were analyzed by means of a X-ray diffraction (XRD) technique. The XRD result confirms the formation of the Ni3Ti phase in the cermets. Due to the formation of the non-magnetic Ni3Ti and the dissolution of Mo in Ni binder phase, the magnetic properties are strongly retarded. The fracture of the cermets is mainly characterized by inter-granular and dimple fractures. Better mechanical properties can be obtained in comparison with conventionally fabricated ones. 相似文献
3.
《Ceramics International》2016,42(14):15274-15284
The effect of WC-Co granules addition on the microstructure and mechanical properties of TiC(nm)-TiN(nm)-Co-Mo-C cermets (shown as Ti(C,N)-based cermets in other part of the paper) was studied in this paper. The results show that the WC-Co granules distribute homogeneously in the matrix of Ti(C,N) based cermets. There was a transitional layer containing intermetallic compound between the WC-Co granules and the matrix of Ti(C,N) based cermets. Transverse rupture strength(TRS) and fracture toughness increase with the increase of WC-Co granules, reach a peak value at 15 vol% addition in comparing with that of without WC-Co granules addition. The toughening mechanisms were crack deflection, branching and trapping. However, when the content of WC-Co granules was higher than 15 vol%, the excessive content of WC-Co granules leaded to voids in the cermets, which decreased the mechanical properties of the cermets. 相似文献
4.
Influence of molybdenum addition on the microstructure and mechanical properties of TiC-based cermets with nano-TiN modification 总被引:11,自引:0,他引:11
Ning Liu Yudong Xu Zhenhong Li Minghai Chen Guanghai Li Lide Zhang 《Ceramics International》2003,29(8):919-925
Effect of Mo addition on the microstructure and mechanical properties of TiC–TiN(nm)–WC–Co–Ni–C system cermets was studied in the work. Specimens were fabricated by conventional powder metallurgy techniques. The microstructure was investigated using transmission electron microscope (TEM) and the scanning electron microscope (SEM). Chemical compositions of different phases such as ceramic phase with core/rim structure [the core being TiC and rim being (Ti,W,Mo)(C,N)] and metallic phase were analyzed quantitatively by EDX. Mechanical properties such as flexural strength, fracture toughness and hardness were also measured. Results show that flexural strength and fracture toughness have a trend to decline with increasing Mo addition, but the change of hardness is not apparent with the increase of Mo addition. Results also reveal that finer microstructure and thicker rim phase will be obtained with the increase of Mo addition. The optimal addition of Mo can be estimated to be 4 wt.% with respect to TiC–10TiN(nm)–15WC–5Co–Mo–5Ni–1C system cermets. Fracture micrographs show that main failure mode of the cermets is a mixed one, i.e., trans-granular and inter-granular fractures both exist. 相似文献
5.
《Ceramics International》2020,46(5):6300-6310
Metallic binder is a key factor affecting the microstructure and mechanical properties of Ti(C,N)-based cermets. To optimize the overall performances, cermets with various weight ratios of Ni/(Co + Ni) ranging from 0 to 1 were fabricated by gas pressure sintering. Microstructure, phase formation, interface structure and related mechanical properties of the sintered cermets were investigated. With the increase of the Ni/(Co + Ni) ratios, the black cores became smaller and grains of Ti(C,N) dispersed uniformly. Compared to the pure Ni or Co, Ni–Co binders accelerated the formation of rim phases, and avoided the nonuniform dispersed binder pools. When the ratio was 0.5, the cermets showed fine grains, uniformly dispersed binders and small lattice misfit of the core-rim interface, exhibiting the optimal mechanical properties, i.e. satisfactory Vickers hardness of 1670 (HV30) Kgf/mm2, bending strength of 1970 MPa and Fracture toughness of 8.94 MPa m0.5. This work sheds light on constructing the relationship between the microstructure, mechanical performance of Ti(C,N)-based cermets and the Ni/Co-based binders. 相似文献
6.
《应用陶瓷进展》2013,112(4):216-223
Short carbon fibre (Cf) reinforced TiCN-based cermets (Cf/TiCN composites) were produced by powder metallurgy method with pressureless sintering technology. The phase evolution, microstructure and fracture morphology of Cf/TiCN composites were investigated. The results showed that TiC, TiN, WC, Cr3C2 and Mo phases disappeared gradually and diffused into core and rim phases by dissolution–reprecipitation process, finally formed new hard TiCN core phases and complex compound (Cr, W, Mo, Ti)(CN) rim phases, with the sintering temperature increasing. The added Cf did not change the ‘core–rim’ microstructure but improved the mechanical properties of TiCN-based cermets. The Cf/TiCN composite containing 3?wt-% Cf achieved the best comprehensive mechanical properties, with fracture toughness and bending strength increasing by about 14.4% and 30.8%, respectively, when compared with the composite without Cf. Toughening and strengthening mechanisms of Cf/TiCN composite were concluded as crack deflection and branch, as well as the pull-out, fracture and bridging of carbon fibres. 相似文献
7.
Microstructure evolution and performance improvement of TiN‐based cermets with carbon addition
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Yuxue Wu Huiwen Xiong Wenmiao Zeng Yue Yuan Xueping Gan 《International Journal of Applied Ceramic Technology》2018,15(5):1190-1198
In this work, TiN‐based cermets with excellent performance and uniform microstructure were successfully manufactured by conventional vacuum sintering with 0‐5 wt% carbon addition at 1500°C. Influence of carbon addition on the microstructure and mechanical properties of cermets was investigated by scanning electron microscope, transmission electron microscope, X‐Ray diffraction, electron probe microanalysis, and mechanical tests. The results showed that small amount of carbon helped to improve significantly the wettability between TiN and Ni/Co, leading to well‐distributed structure and perfect core‐rim phases. As the carbon content increased from 0 to 5 wt%, mechanical properties of cermets increased initially, displayed a maximum and then decreased. For the experimental conditions considered, the cermets with 3 wt% carbon addition revealed best mechanical properties. The relative density, the transverse rupture strength, fracture toughness, and Rockwell hardness of the cermets were 99.78%, 1836 MPa, 14.7 MPa m1/2, and 88, respectively. 相似文献
8.
9.
In this study, Ti(C,N)-WC-NbC-ZrC-Co-Ni cermets were prepared by sintering-hip at 1450?°C. The effect of ZrC addition on the microstructure, mechanical properties, oxidation resistance and wear resistance of Ti(C,N)-WC-NbC-Co-Ni cermets were explored in detail. The results show that ZrC addition plays the role of inhibitor in the dissolution–reprecipitation process, which can increase the wear-resistant carbide phases and inhibit the precipitation of brittle (Ti,W,Nb)(C,N) rim phase. Therefore, the core-rim structures are refined and the Nb content in binder increases, which enhance mechanical properties and oxidation resistance of cermets. With the increasing ZrC content, the oxidation resistance of cermets can be improved constantly, while the transverse rupture strength, fracture toughness and wear resistance of these cermets increase first and then decrease. The cermet with 1?wt% ZrC exhibits the transverse rupture strength of 2549?MPa and highest fracture toughness of 13.0?MPa?m1/2. The oxidation weight gain of cermets containing 5?wt% ZrC after holding 100?h at 750?°C in air is 2.8?×?10?6 g?mm?2, which is only 22% of that in the cermets without ZrC addition. 相似文献
10.
《Ceramics International》2021,47(21):30113-30128
To repair the surface defects of spline shaft and improve wear resistance, the coarse TiC reinforced Ni-based composite coatings were fabricated on the spline shaft surface by laser cladding with six types of precursors containing Ni45, coarse TiC, and fine TiN powder. The effects of ceramic content and fine TiN addition on the formability, microstructure, and mechanical properties of the coatings were studied comprehensively. In TiC reinforced Ni-based coatings 1–3 without fine TiN addition, the porosity decreased from 20.415 % to 0.571 % with the increase of TiC concentration. The coatings mainly consist of CrB, Cr7C3, Cr23C6, coarse TiC, and γ-Ni. With the addition of fine TiN, the length of the ceramic phases in coatings 1#–3# decreased slightly, while volume fraction and porosity increased. Moreover, the ring-shaped Ti (C, N) phases were also detected at the edges of both undissolved TiC and TiN particles, which improved the bonding force between ceramics and matrix. Besides, these ceramics inhibited the generation of columnar crystals and eliminated the heat-affected zone. The performance test results show that the coating 3# with 30 wt% TiC and 6 wt% TiN exhibits the best wear resistance despite slightly decreased hardness, and its friction coefficient of 0.409 and wear rate of 42.44 × 10−6 mm3 N−1·m−1 are, respectively, 0.667 and 0.307 times those of the substrate. Based on the additive/subtractive hybrid manufacturing technology, the optimized coatings were ground to obtain the finishing surface, which indicates that the coarse TiC reinforced coating can be employed in repairing the damaged parts. 相似文献
11.
用粉末冶金真空烧结法制备了超细晶粒碳氮化钛[Ti(C,N)]基金属陶瓷.研究了原始粉末粒径对Ti(C,N)基金属陶瓷微观结构和力学性能的影响.结果表明:在化学成分相同的条件下,晶粒细化使材料的Vickers硬度和抗弯强度上升,但断裂韧性有所下降.在超细晶粒Ti(C,N)基金属陶瓷微观组织中出现了一种新型的白芯/灰壳结构和一种特殊化合物(Ni2Mo2.5W1.3)Cx.初步研究表明:由于原始粉末粒径微小,促进了扩散反应因而生成了这种芯/壳结构.芯/壳结构有利于提高材料的抗弯强度和断裂韧性.(Ni2Mo2.5W1.3)Cx有利于提高材料的Vickers硬度,但是降低了Ti(C,N)基金属陶瓷的抗弯强度和断裂韧性. 相似文献
12.
Xiangyu Xu Yong Zheng Jiajie Zhang Zheng Ke Hao Wu Zhengkai Yang 《Ceramics International》2021,47(12):16786-16793
Complete solid-solution Ti(C,N)-based cermet, with no typical core-rim structure, was synthesized through mechanical activation and subsequent in situ carbothermal reduction method. XRD, SEM, TEM, and C/N analysis were used to investigate the microstructure, phase transformation, and the interfacial characteristics of the present cermets. During solid-state sintering, the (Ti,Mo)C/(Ti,Mo)(C,N) phases formed through the transformation of Mo-based solid solution which generated by mechanical activation. Then, the formed (Ti,Mo)C/(Ti,Mo)(C,N) continuously dissolved into the nickel-based binder above 1100 °C. It was found that in the subsequent stage of liquid sintering, the mechanical activation and also the presence of extremely fine TiC/Ti(C,N) particles accelerated the Mo diffusion into the hard phase, resulting in a large quantity of (Ti,Mo)(C,N) solid solutions formed in the nickel-based binder. Finally, complete (Ti,Mo)(C,N) solid-solution phase was obtained via dissolution and re-precipitation. The higher toughness and transverse rupture strength (TRS) of the synthesized new cermet, as compared with traditional cermets, were mainly caused by the increased crack deflection and transgranular fracture of the novel cermets. Moreover, the interface among the Ni-based binder phase and complete solid solution hard phase exhibited a semi-coherency state with high-density dislocations, which also significantly improved the TRS and toughness of the synthesized cermets. 相似文献
13.
《Journal of the European Ceramic Society》2020,40(7):2527-2532
Ceramic-metal composites TiC–High-Entropy Alloy (HEA) CoCrFeNiMe (Me = Mn, Ti or Al) were first produced by combustion synthesis method. Self-sustained synthesis occurs due to heat release from exothermic reaction Ti + C = TiC; the binder content was varied between zero and 40–50 wt.%. The combustion velocity and temperature gradually decreased with increasing binder content. Resultant materials consist of TiC grains and two-phase (fcc and bcc) binder. Vickers microhardness (100 g) of compacted cermet materials with 30 wt.% of binder was in the range of 10–17 GPa and increased with increasing bcc to fcc ratio. Based on experimental results and thermodynamic calculations, the mechanism of microstructure formation in TiC–HEA cermets was suggested. 相似文献
14.
《Ceramics International》2016,42(6):6858-6867
TiC whisker reinforced ultra-fine TiC-based cermets were fabricated and their microstructures as well as mechanical properties were characterized and compared with microsized and ultra-fine cermets. The effects of high energy milling and subsequent annealing on the composition and microstructure of microsized TiC powders were studied. It was shown that the particle size distribution of TiC powders played a critical role in determining cermets׳ microstructure and properties. Inverse grain (White core with grey rim) only exists in ultra-fine cermet with a narrow size distribution of annealed TiC powders. Large discrepancy of larger TiC powders (microsized particles or whiskers) and ultra-fine particles in size resulted in a bimodal grain size feature. Additionally, mechanical property testing was conducted and was related to the microstructural features. The whisker reinforced cermets own much higher toughness of 12.43 Mpa m1/2 than the microsized and ultra-fine cermets, with a hardness (Hv30, 1620) between them. 相似文献
15.
Xiyue Kang Nan Lin Yuehui He Qiankun Zhang Meimei Zhang Yan Yan Yi Liu 《Ceramics International》2021,47(14):19934-19944
Ti(C,N)-WC-Mo2C-TaC-Co-Ni cermets with various content of La2O3 were prepared by gas-pressure sintering at 1450 °C. The effects of ultrafine La2O3 additions (0, 0.05, 0.1 and 0.2 wt%) on the microstructure, mechanical properties, wear resistance and cutting performance of cermets were explored. In the microstructure of cermets, the La2O3 particles and dissolved La element in binder phases were observed, which could inhibit the dissolution-precipitation process of ceramics phases during liquid-sintering. Furthermore, the La2O3 could absorb and react with the impurity Al element with low melting point from raw powders, avoiding the appearance of liquid phase at the low temperature and partial overheating during sintering process. These mechanisms could inhibit the abnormal growth of Ti(C,N) core-(Ti,W,Mo,Ta)(C,N) rim structures effectively, leading to the thinning of brittle rim phases and coarsening of wear-proof Ti(C,N) particles. The decrease of proportion of brittle rim phase and ultrafine Ti(C,N) particles promoted the fracture toughness. The increase of proportion and grain size of Ti(C,N) improved the hardness, wear resistance and cutting performance significantly. However, the excessive addition of La2O3 would result in the agglomeration of La2O3, causing the sharp decline of mechanical properties and cutting performance. The cermet with 0.1 wt% La2O3 addition possessed the optimal mechanical properties with Vickers hardness, transverse rupture strength and fracture toughness of 1710 (HV30) Kgf/mm2, 2480 MPa and 11.7 MPa m1/2, respectively. 相似文献
16.
《Journal of the European Ceramic Society》2002,22(14-15):2587-2593
Starting from commercial nanosize TiN and carbon black powders, this study set up a synthesis of fine and pure Ti(C,N) powders. The best experimental conditions were found using a mixture TiN+10 wt.% of C processed at 1430 °C for 3 h under flowing Argon. The as-produced Ti(C,N) powder showed regularly shaped particles (100–300 nm), little agglomeration and a C/(C+N) atomic ratio ranging from 0.4 to 0.6. A mixture of Ti(C,N) +15.3 wt% of WC and 9.1 wt% of Ni+Co was prepared and hot pressed at 1620 °C for 30 min (5 MPa of applied pressure). Microstructure and some properties of the sintered ceramic–metal composite (cermet) was investigated by SEM-EDX and XRD. The material exhibited a refined microstructure, but also the presence of textured flaws of several tenths of microns, attributed to not-optimized sintering conditions. The results were compared with those obtained from a cermet manufactured with the same nominal formulation but with commercial TiC0.5N0.5 raw powder. 相似文献
17.
Guotao Zhang Yong Zheng Wei Zhou Yijie Zhao Jiajie Zhang Zheng Ke Lixin Yu 《Ceramics International》2018,44(3):3092-3098
Ti(C,N)-based cermets were prepared by in situ carbothermal reduction of TiO2 and subsequent liquid phase sintering in one single process in vacuum. The densification behavior, phase transformation, and microstructure evolution of the cermets were investigated by DSC, XRD, SEM, and EDX. The results showed that the carbothermal reduction of TiO2 was completed below 1250 °C, and Ti(C,N)-based cermets with refined grains were obtained after sintered at 1400 °C for 1 h by this method. The hard phase of the cermets mainly exhibited white core/gray rim structure, in great contrast to the typical black core/gray rim structure of hard phase in traditional cermets. Ti(C,N)-based cermets prepared by this novel method showed excellent mechanical properties with a transverse rupture strength of 2516±55 MPa, a Rockwell hardness of 88.6±0.1 HRA, and a fracture toughness of 18.4±0.7 MPa m1/2, respectively. 相似文献
18.
Guotao Zhang Yong Zheng Wei Zhou Zheng Ke Weimin Ding Lixin Yu Yonglin Yan 《Journal of the American Ceramic Society》2019,102(5):3009-3018
Ti(C,N)-based cermets were prepared by in situ carbothermal reduction in TiO2 and subsequent liquid phase sintering under vacuum. The prepared cermets were examined using XRD, SEM, TEM, and EDX. During solid-state sintering, fine TiC particles were formed through the carbothermal reduction in TiO2. A great number of (Ti,W,Mo)C complete solid solutions containing more W and Mo subsequently formed through the counter diffusion of the fine TiC and carbides. The majority of the coarse TiN particles in the raw powders remained undissolved. During liquid phase sintering, Ti-based carbonitride complex solid solutions with less W or Mo precipitated on the coarse TiN particles and fine (Ti,W,Mo)C particles, resulting in black core/gray rim structures and white core/gray rim structures, respectively. Moreover, small amounts of Ti-based carbonitride complex solid solutions precipitated directly from the liquid binder phase in some areas enriched in W and Mo during the cooling stage after sintering, resulting in coreless grains. Ultimately, after being sintered at 1400°C for 1 hour, the present cermets were characterized with white core/gray rim grains, black core/gray rim grains and a few gray grains. In addition, the interfaces between the black core/gray rim grains and binder phase were atomically smooth, exhibiting a orientation relationship with a perfect coherency state. 相似文献
19.
Huiwen Xiong Yu Wen Zhiyou Li Kechao Zhou 《Journal of the American Ceramic Society》2019,102(7):4296-4305
Reactive sintering of crushed metals and carbon is advantageous for preparing toughened complete solid-solution cermets (CSCs). Here, dual-grained (Ti0.6, W0.4)C–18Ni cermets were prepared using a two-step carbonization method. High-energy milling of Ni–Ti–W–C (Ni(Ti0.6, W0.4)4C) mixture afforded NiTiW solid solution, which was then transformed into Ni6W6C by heating at 1250°C. Twinned (Ti, W)C platelets were formed by the carbonization of Ni2W4C during liquid sintering. W atoms that accumulated in the (111) planes of TiC promoted the {111} twin formation, leading to sandwich-type (Ti, W)C platelets. Dense (Ti0.6, W0.4)C–18Ni cermets were obtained by hot isostatic press sintering in Ar with satisfactory Hv of 12.8 ± 0.2 GPa, high strength of 1960 ± 84 MPa and toughness of 15.80 ± 0.6 MPa·m1/2. A higher sintering temperature or graphite content accelerated the carbonization, resulting in coarser platelets with decreased aspect ratio. This study provides a new approach to modify the microstructure of CSCs and a method for preparing dual-grained cermets. 相似文献
20.
Guangyu He Li Wang Jiao Chen Danyang Sun Yan Chai Zhihao Fang 《Journal of the American Ceramic Society》2022,105(5):3153-3164
Sand erosion is a major factor that shortens the service life of aircraft in desert regions. The anti-erosion performance of titanium alloys may be improved using TiN coatings. However, few studies have employed Ti sputtering on Ti transition layers to improve the erosion resistance of the coatings. Herein, TiN coatings with a sputtering layer between the Ti transition layer and the TiN layer were deposited on a Ti–6Al–4V alloy by filtered cathodic vacuum arc deposition. For comparison, another group of TiN coatings without a Ti sputtering layer but processed using the same deposition parameters were prepared. The effects of the nanoscale sputtering layer on the microstructure, mechanical properties, and anti-erosion performance of the coatings were investigated using scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and nanoindentation. The results show that the introduction of a Ti sputtering layer promoted the growth of TiN grains, leading to the formation of finer and denser TiN columnar grains. The preferred orientation of the coatings with the sputtering layer is (111) plane, whereas that of the coatings without the sputtering layer is (200) plane. The TiN coatings containing a sputtering layer exhibit higher hardness, elastic modulus, and H3/E2 ratio, which enhances the anti-erosion performance of the coatings. The coatings with a sputtering layer exhibited better erosion resistance (erosion rate reduced by 75%) than the coatings without a sputtering layer. The underlying mechanism to understand the effect of the sputtering layer on the erosion resistance was discussed based on variations in the microstructure and mechanical properties of the coatings with and without the Ti sputtering layer. Ti sputtering layer was finally proved to be an effective method to improve the erosion resistance of TiN coatings. 相似文献