Mo含量对Ti(C,N)基金属陶瓷在H_2SO_4溶液中腐蚀性能的影响

本文以四种不同Mo含量的Ti(C,N)基金属陶瓷为研究对象,通过组织观察、孔隙率测定、抗弯强度、硬度测试方法研究了Mo含量的变化对Ti(C,N)-Ni金属陶瓷组织和性能的影响,试验结果表明:Ti(C,N)基金属陶瓷呈现典型的芯-环结构,随Mo添加量增加,晶粒发生明显细化,抗弯强度及硬度增加。通过电化学测试方法,如动电位极化、交流阻抗曲线测定(EIS)、静态浸泡腐蚀试验等方法,结合腐蚀形貌观察,研究了不同Mo含量对Ti(C,N)基金属陶瓷在0.2 mol/L H2SO4溶液中的电化学性能和腐蚀性能的影响规律。含有Mo的Ti(C,N)-Ni金属陶瓷的极化曲线存在两个钝化区,其中一个为"伪钝化"区,随Mo元素含量增加,其维钝电流密度减小,维钝区间扩大。交流阻抗试验显示,Ti(C,N)-Ni金属陶瓷的反应阻抗值会随着Mo含量的增加而变大。Ti(C,N)-Ni金属陶瓷在试验溶液中的腐蚀速率也会随Mo含量的增加而明显下降。主要原因是由于随着Mo添加量的增加,降低陶瓷的孔隙率,增大了材料的致密度,改善了硬质相和粘结相之间的润湿性;而且溶解于粘结相中的Mo含量提高,提高了粘结相的耐蚀性,从而降低了金属陶瓷在H2SO4溶液中的腐蚀速率。     

Ti(C,N)-Ni/Cr金属陶瓷在HCl溶液中耐蚀性研究

本文通过开路电位监测、动电位极化、交流阻抗曲线测定、静态浸泡腐蚀试验等方法,结合腐蚀形貌电镜观察,研究了Ti(C,N)-Ni/Cr金属陶瓷在1 mol/LHCl溶液中的腐蚀行为。试验结果表明:与粘结相全部为Ni的Ti(C,N)基金属陶瓷相比,添加4%Cr做粘结相后,使金属陶瓷的开路电位明显正移。而且可以明显减小其"伪钝化区"的维钝电流密度,扩大维钝区间;提高Ti(C,N)基金属陶瓷在HCl溶液中耐蚀性。其主要原因是由于Cr溶入粘结相Ni后,提高了粘结相的抗H+与Cl-腐蚀能力。     

粘结剂成分对Ti(C,N)基金属陶瓷腐蚀行为的影响

研究了含38 wt% Ni或Ni–20Cr粘结剂的2种Ti(C,N)基金属陶瓷在0.2 M H2SO4和0.2 M NaOH溶液中的室温腐蚀行为。在0.2 MH2SO4溶液中,2种金属陶瓷的腐蚀行为和耐蚀性存在一些明显的差异：与以Ni作粘结剂的金属陶瓷不同,以Ni–20Cr作粘结剂的金属陶瓷浸泡过程中表面自发生成NiO、Ni(OH)x(SO4)y、Cr2O3和Cr(OH)3,致使粘结相溶解十分缓慢;动电位极化过程中不发生钝化,伪钝化后电流密度增加较快。在0.2 M NaOH溶液中,2种金属陶瓷的腐蚀行为和耐蚀性无明显差异：浸泡过程中陶瓷晶粒溶解十分缓慢,同时生成NiOOH和Cr6+化合物;动电位极化过程中不发生钝化,但发生伪钝化。     

钛的碳氮化物固溶与单组元对Ti(C,N)基金属陶瓷电化学腐蚀性能的影响

以TiC0.7N0.3-10％ WC-4％ Mo2C-3％ TaC-2.4％ Cr3C2-10％ Ni-10％ Co和TiC-10％TiN-10％WC-4％Mo2C-3％TaC-2.4％Cr3C2-10％Ni-10％Co 2种Ti(C,N)基金属陶瓷为研究对象,采用Tafel曲线与Nyquist图谱研究2种金属陶瓷在pH=1的H2SO4溶液与pH=13的NaOH溶液中的电化学腐蚀行为,采用扫描电镜观察合金的腐蚀表面.结果表明,与单组元原料相比,以固溶体为原料制备Ti(C,N)基金属陶瓷在强酸、强碱性溶液中的腐蚀速率均明显降低,耐腐蚀性显著提高;Ti(C,N)基金属陶瓷在碱性溶液中的耐腐蚀性能优于其在酸性溶液中的耐腐蚀性能.Ti(C,N)基金属陶瓷的腐蚀机理是:与腐蚀溶液接触时,合金中粘结相优先发生腐蚀,产生活性溶解,硬质相骨架裸露在合金表面,硬质相发生局部腐蚀.     

Mo_2C对Ti(C,N)基金属陶瓷冲刷腐蚀性能的影响

采用传统的粉末冶金烧结工艺制备了4组不同Mo2C含量的Ti(C,N)基金属陶瓷。用洛氏硬度计、金相显微镜和三点弯曲法分别测得试样的硬度、孔隙度及抗弯强度。通过观察发现Ti(C,N)基金属陶瓷的组织呈现典型的芯-环结构,并随Mo2C含量的增加,组织细化明显。对冲刷腐蚀后的试样表面采用SEM、EDS等方式进行研究测试,结果发现Mo2C能提高金属陶瓷的抗冲刷腐蚀性能,但添加过多会降低该性能。     

Mo含量对Ti(C,N)基金属陶瓷组织和性能的影响

Ti(C,N)基金属陶瓷是一种新型工具材料,在高速切削刀具中得到广泛应用。本文介绍了金属陶瓷中Mo或Mo2C的作用,并综述了国内外关于Mo或Mo2C对Ti(C,N)基金属陶瓷显微组织和性能的影响。     

WC粒径对Ti(C,N)基金属陶瓷组织和性能的影响

用真空烧结法制备了添加微米级和亚微米级WC的Ti(C,N)基金属陶瓷,研究了WC粒径对Ti(C,N)基金属陶瓷组织和性能的影响。研究结果表明:添加微米级和亚微米级WC的Ti(C,N)基金属陶瓷试样均呈现出典型的"芯-环"结构,但在添加了亚微米级WC的试样中出现了"白芯-灰环"结构。同时,随着原始WC颗粒粒径的变小,其硬质相和黑色的芯相尺寸变小,而且黑色的芯相体积分数也变小。能谱分析表明,白色芯相具有与环形相相同的元素组成,但白色芯相含有较多的W和Mo元素。力学性能测试表明,添加亚微米级WC的金属陶瓷的抗弯强度要优于添加微米级WC的金属陶瓷,但硬度却偏低。     

(Ti,La)(C,N)基金属陶瓷复合材料制备及性能研究

采用高温碳管炉制备了平均粒度约为1.2μm的(Ti,La)(C,N)复式碳氮化物粉末,并将其应用于(Ti,La)(C,N)基金属陶瓷的制备。研究稀土La元素的固溶含量对(Ti,La)(C,N)基金属陶瓷的组织结构和性能的影响,同时对比了La_2 O_3的直接加入对Ti(C,N)基金属陶瓷组织结构和性能的影响。通过X衍射和扫描电镜对两组金属陶瓷进行研究分析,结果表明:La含量相同时,相比于直接添加La_2 O_3的Ti(C,N)基金属陶瓷,(Ti,La)(C,N)基金属陶瓷各项性能指标均有提高,其抗弯强度提高了约20%,硬度也稍有提升,且当(Ti,La)(C,N)中La元素固溶0.25%时,物理和力学性能最佳;(Ti,La)(C,N)基金属陶瓷强化机制主要表现为固溶强化。     

烧结工艺和Y_2O_3添加量对Ti(C,N)基金属陶瓷显微组织和力学性能的影响

以TiC、TiN、Ni、Co等粉末为主要原料,以稀土Y2O3为添加剂,采用无压烧结技术制备Ti(C,N)基金属陶瓷,研究烧结工艺和稀土Y2O3添加量对Ti(C,N)基金属陶瓷显微组织和力学性能的影响。结果表明:随着温度的升高,TiC、TiN、WC、Cr3C2、Mo等相逐渐消失,向硬质芯相扩散发生固溶,经溶解-析出过程,最终形成新的Ti(C,N)硬质相和(Cr,W,Mo,Ti)(C,N)固溶体环形相,黏结金属Ni和Co主要以Ni相、TiCo和Co3W3C中间相的形式存在;稀土Y2O3的添加未改变Ti(C,N)基金属陶瓷烧结过程中的相结构演变过程,材料的显微硬度、抗弯强度和断裂韧性均随Y2O3添加量的增加呈先增加后降低的趋势,当Y2O3的加入量为0.8%(质量分数)时,Ti(C,N)基金属陶瓷的力学性能最佳,样品的显微硬度、抗弯强度和断裂韧性相比1450℃烧结50 min样品的分别提高了7.9%、45.8%和6.1%。     

CeO2添加量对Ti(C,N)基金属陶瓷显微结构和力学性能的影响

采用真空烧结工艺制备了(56-x)Ti(C0.5,N0.5)-20WC-3.5Mo2C-20(Co+ Ni)-xCeO2(x=0,0.05％,0.1％,0.2％)系列金属陶瓷,研究了CeO2添加量对Ti(C,N)基金属陶瓷显微结构和力学性能的影响.结果 表明:添加适量的CeO2有利于Ti(C,N)金属陶瓷显微组织细化,使硬质相颗粒尺寸减小,而且分布更加均匀,从而提高其力学性能.此外,添加CeO2后金属陶瓷中裂纹扩展过程产生较多的桥接现象,使其具有较高的断裂韧性.随着CeO2添加量增加,Ti(C,N)金属陶瓷的密度和力学性能先增大后减小,CeO2添加量为0.1％时,金属陶瓷的密度、硬度、抗弯强度和断裂韧性分别为6.51 g/cm3、91.6 HRA、1577 MPa和9.11 MPa·m1/2.     

Corrosion behavior of Ti(C,N)-Ni/Cr cermets in H2SO4 solution

The effects of partial substitution of Ni with Cr on the microstructure and corrosion resistance of Ti(C,N)-based cermets in H₂SO₄ solution were investigated in this paper. The results showed that partial substitution of Ni with Cr had a minor effect on the microstructure, whereas the hardness of the Ti(C,N)-based cermets could be improved for dissolution of Cr in Ni binder. The corrosion behavior of Ti(C,N)-based cermets with different Cr content in 0.2 mol/L H₂SO₄ solution was also studied via potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and corrosion test. The tested Ti(C,N)-Ni/Cr cermets had three typical passive regions. The current of the first passive region was reduced and the passive range was enlarged with the increase of Cr content in binder attributed to the synergistic effect of Ti-based and Cr-based passive layers. But the remaining passive regions were pseudopassive regions. The EIS results also demonstrated that the impendence of the reaction rose with the increase of Cr content in binder. Moreover, the corrosion resistance of cermets in H₂SO₄ solution was improved remarkably by Cr dissolving in the binder, which gave rise to the enhanced passivation ability.     

氮含量对Ti(C,N)基金属陶瓷显微组织与磨粒磨损行为的影响

采用真空烧结方法制备了4种氮含量的Ti(C,N)基金属陶瓷,测试了试样的抗弯强度、硬度、断裂韧性等力学性能,用扫描电镜、能谱仪等研究了N含量对其显微组织及磨粒磨损行为的影响。结果表明:在一定范围内随N含量的增加,硬质相芯部逐渐细化且分布均匀,环形相厚度变薄、体积分数减小;磨粒磨损形貌中犁沟所占的比例减少,微观脆性断裂形成的凹坑增加,耐磨粒磨损性能逐渐提高。随N含量增加,Ti(C,N)基金属陶瓷的抗弯强度呈现出先增加后减小的趋势,断裂韧度逐渐递减,硬度变化不大。当N含量为3.6%时(文中含量均为质量分数),Ti(C,N)基金属陶瓷综合力学性能最佳,其抗弯强度为1 873 MPa,硬度为89.9 HRA,断裂韧度为20.7 MPa.m1/2。     

Erosion-corrosion behavior of Ti(C,N)-based cermets containing different secondary carbides

The present work investigated the effects of secondary carbides (Mo₂C\WC\TaC\NbC) on the erosion-corrosion behavior of Ti(C,N)-based cermets. The results indicate that the erosion-corrosion resistance of Ti(C,N)-based cermets is enhanced in the order of NbC, TaC, WC and Mo2C addition. The contribution of erosion to the erosion-corrosion of Ti(C,N)-based cermets is much more significant than that of corrosion, and it increases with the decreased mechanical properties. The synergistic effect plays a dominant role in the degradation of Ti(C,N)-based cermets in erosion-corrosion conditions. There are two modes to ceramic phase degradation in erosion conditions: large ceramic grains are prone to deterioration through crack initiation and propagation → grain fracture → fragment removal; finer ceramic grains trend to be pulled out after the deterioration of binder and interface. The binder loss is determined by the corrosion resistance of binder, the erosion resistance of binder and the erosion resistance of ceramic phase.     

冷却方式对Ti(C,N)基金属陶瓷显微组织和力学性能的影响

采用真空烧结工艺制备微米级Ti(C,N)基金属陶瓷。通过XRD、SEM等研究了液相烧结后,冷却方式对微米级Ti(C,N)基金属陶瓷显微组织、力学性能的影响。试验结果表明,烧结后随炉冷却,烧结体可获得较均匀的显微组织,且环形相完整且厚度适中;冷却时,在液相阶段增加保温台阶,晶粒有所长大且有发生团聚现象发生,环形相变厚,导致材料的力学性能下降。微米级Ti(C,N)基金属陶瓷烧结后合适的冷却方式为无保温、随炉冷却。     

原始粉末粒度组合对Ti(C,N)基金属陶瓷组织和性能的影响

采用粉末冶金方法制备了Ti(C,N)基金属陶瓷,研究了TiC和TiN在不同粒度组合下,Ti(C,N)基金属陶瓷的组织和性能。利用SEM、XRD等分析手段对所制备的金属陶瓷进行分析。结果表明,采用微米级TiC和纳米级TiN粒度组合得到的Ti(C,N)基金属陶瓷综合力学性能最好。其抗弯强度达到了1 052.8 MPa,断裂韧性达到了9.3 MPa·m1/2。     

Effect of VC addition on sinterability and microstructure of ultrafine Ti(C, N)-based cermets in spark plasma sintering

The effect of vanadium carbide (VC) addition on the sinterability and the microstructure of ultrafine Ti(C, N)-based cermets consolidated through spark plasma sintering (SPS) was systematically investigated using optical microscope, scanning electron microscope (SEM) with X-ray energy dispersive spectrometer (EDS), X-ray diffractometer (XRD) and transmission electron microscope (TEM). Our results reveal that the addition of VC increases the porosity of sintering body and depresses the sinterability of Ti(C, N)-based cermets. It is also found that the VC addition has a significant influence on the microstructure of ultrafine Ti(C, N)-based cermets, which inhibits the dissolution of titanium-containing compounds and the formation of inner rim phase and outer rim phase, thus preventing from grain growth. Owing to the depressed dissolution and precipitation, nitrogen liberation is mitigated, therefore resulting in less amount of graphite phase in the samples. In substance, VC changes the solubility of metallic elements in the binder, which makes more elements of Mo and W to be reserved in the binder and thus greatly decreases the content of titanium dissolved into the binder. The re-building solubility rule determines the development of phases and microstructure.     

Erosion–corrosion behavior of Ti(C,N)-based cermets with different TiN contents

Ti(C,N)-based cermets are fabricated with diverse contents of TiN addition by traditional powder metallurgy technique. The microstructure and properties are investigated and discussed. The influence of TiN content on the erosion and erosion–corrosion resistance is researched under alkaline conditions. Results reveal that the grain size decreases along with the increase of TiN. However, too much TiN results in incompact material and residual porosities in cermets. The grain size plays an important role in wear behavior. The effect of TiN content on erosion–corrosion of Ti(C,N)-based cermets is the same as that on erosion. It is advantageous for the wear resistance to add a small amount of TiN. Excessive TiN makes the wear resistance decrease on the contrary. In alkaline slurry, the cermets with coarse grains deteriorate largely due to corrosion which decreases the mechanical properties and speeds up the total loss of material. Nevertheless, the mechanical erosion is responsible for the degradation of cermets with fine grains. Cermets with 7.5 wt.% TiN addition have the highest erosion and erosion–corrosion resistance.     

Effects of Cr3C2 addition on the corrosion behavior of Ti(C,N)-based cermets

The Ti(C, N)-based cermets with different Cr₃C₂ addition were prepared and the effects of Cr₃C₂ addition on the microstructure and properties of cermets were discussed. The corrosion behavior of the cermets with different Cr₃C₂ addition was investigated emphatically in 2 mol/L HNO₃ solution. The results indicate that there is no obvious effect of Cr₃C₂ addition on the densification of the cermets, and all cermets are almost fully densified during sintering. The thickness of rim phase is reduced and the core size is increased remarkably in the cermets with 1 wt.% and 3 wt.% Cr₃C₂ addition; the grains are refined significantly in the cermets with the increase of Cr₃C₂ addition to 5 wt.%. The hardness and transverse rapture strength of the cermets are improved with Cr₃C₂ added properly. In HNO₃ solution, the corrosion resistance of cermets is improved remarkably by Cr₃C₂ addition. The corrosion of binder phase is predominant in the cermets in which the Ni binder phase without Cr has lower corrosion resistance than the rim phase; whereas the corrosion resistance of binder phase with high Cr content is better compared to the rim phase, so that the degradation of rim phase is predominant and a reticulate binder phase forms. With the increase of Cr₃C₂ addition, the Mo content in rim increases, and it is bad for the corrosion resistance of rim phase. Additionally, the inner rim phase has lower corrosion resistance than the outer rim phase owing to the higher Mo content.     

EFFECT OF Mo AND Mo2C ON THE MICROSTRUCTURE AND PROPERTIES OF THE CERMETS BASED ON Ti（C,N）

Effect of Mo and Mo2 C on the microstructure and properties of Ti（C,N）-based cermets was investigated in this article. The results have indicated that the weight percentage of Mo from 5 to 10 can reduce Ti（C,N） grain diameter and thickness of the rim, and Ti（C,N） grain can be wetted by Ni-Cu-Mo liquid so as to get small contiguity of Ti（C,N） grain. In that way, the transverse rupture strength of Ti（C,N）-based cermets has reached 1800-1900 MPa; the fracture toughness has been due to 16-18 MPa.m1/2. But 15 wt pct Mo was not more effective on Ti（C,N）-based cermets, because the thickness of the rim becomes larger. In the circumstance of Mo2 C, 5 wt pct Mo2 C was good for microstructure and properties of Ti（C,N）-based cermets, but 11 wt pct Mo2C has resulted in larger contiguity of Ti（C,N） grain and big Ti（C,N） grain diameter so as to reduce transverse rupture strength and fracture toughness. So that, the effect of Mo on Ti（C,N）-based cermets is better than Mo2C.     

碳添加量对Ti(C,N)基金属陶瓷组织和性能的影响

碳含量对Ti(C,N)基金属陶瓷的显微组织和机械性能有着重要影响。本文综述了碳含量对Ti(C,N)基金属陶瓷晶粒大小、相成分和力学性能的影响,分析了影响机制。在一定范围内适当调整碳含量,可以获得综合性能良好的Ti(C,N)基金属陶瓷。