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。     

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.     

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。     

WC-Co-(Ni)-(Cr)硬质合金在中性溶液中的腐蚀行为

以WC粉、Co粉、Ni粉及Cr3C2粉为原料,采用粉末冶金方法制备了3组不同粘结相成分的WC-Co-(Ni)-(Cr)硬质合金,通过极化曲线测试和浸泡实验研究了3组合金在中性溶液中的腐蚀行为,并采用扫描电镜、能谱分析、X射线光电子能谱(XPS)和EBSD等手段对其腐蚀机理进行了探讨。结果表明,WC-Co和WC-Co-Cr硬质合金在中性溶液中主要发生粘结相Co的腐蚀,浸泡产生的腐蚀产物主要是Co(OH)2;添加Cr将提高WC-Co硬质合金在中性溶液中的耐腐蚀性能,这可能与Cr的添加明显降低了粘结相中密排六方Co的含量有关;同时添加Ni和Cr可进一步提高WC-Co合金在中性溶液中的耐腐蚀性能,在pH=7的Na2SO4溶液中浸泡480 h后,WC-Co-Ni-Cr合金发生很少量的腐蚀。     

WC-Co-(Ni)-(Cr)硬质合金在中性溶液中的腐蚀行为

以WC粉、Co粉、Ni粉及Cr_3C_2粉为原料,采用粉末冶金方法制备了3组不同粘结相成分的WC-Co-(Ni)-(Cr)硬质合金,通过极化曲线测试和浸泡实验研究了3组合金在中性溶液中的腐蚀行为,并采用扫描电镜、能谱分析、X射线光电子能谱(XPS)和EBSD等手段对其腐蚀机理进行了探讨。结果表明,WC-Co和WC-Co-Cr硬质合金在中性溶液中主要发生粘结相Co的腐蚀,浸泡产生的腐蚀产物主要是Co(OH)2;添加Cr将提高WC-Co硬质合金在中性溶液中的耐腐蚀性能,这可能与Cr的添加明显降低了粘结相中密排六方Co的含量有关;同时添加Ni和Cr可进一步提高WC-Co合金在中性溶液中的耐腐蚀性能,在pH=7的Na2SO4溶液中浸泡480 h后,WC-Co-Ni-Cr合金发生很少量的腐蚀。     

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。     

镍、铬对硬质合金酸性盐雾腐蚀性能的影响

本文采用传统粉末冶金工艺制备了WC-8%Co、WC-6%Co-2%Ni-0.4%Cr3C2、WC-8%Ni-0.4%Cr3C2硬质合金样品,利用酸性盐雾试验、极化曲线测试、扫描电镜观察和能谱分析等手段,研究了添加Ni、Cr等元素对硬质合金酸性盐雾环境中腐蚀行为的影响。试验结果表明:WC-Co硬质合金在酸性盐雾环境下由于粘结相标准还原电极电位低,更容易发生电化学腐蚀,造成粘结相流失;添加Ni和Cr,可以提高WC-Co硬质合金的电极电位,降低极化电流密度,提高其在酸性盐雾溶液中的抗腐蚀能力;扫描电镜和能谱分析结果表明添加Ni和Cr,可以降低硬质合金在酸性盐雾溶液中粘结相的流失。     

Mo_2C对Ti(C,N)基金属陶瓷腐蚀性能的影响

通过静态浸泡腐蚀和动电位极化两种方法,研究了Mo2C对Ti(C,N)基金属陶瓷在NaOH溶液中腐蚀性能的影响。实验结果表明:Ti(C,N)基金属陶瓷的耐蚀性明显优于WC-Co硬质合金;添加Mo2C可以大幅度提高Ti(C,N)基金属陶瓷的机械性能,硬度从91.2到94.0 HRA和抗弯强度从930到1 350 MPa,但会降低金属陶瓷的耐蚀性能;由于Mo2C的加入,会使金属陶瓷的动电位极化曲线出现两个钝化区,但是两个钝化区域的电流均未达到真正的钝化电流(10-5A/cm2),因而这些钝化现象均为伪钝化;在经动电位极化后的试样表面,粘结相Ni和白色的内环相均会被腐蚀,其中内环相为富Mo的(Mo,Ti)(C,N)固溶体,其耐腐蚀性较未溶的Ti(C,N)芯更差。随着Mo2C添加量的提高,内环形相的厚度随之会增加,从而降低了Ti(C,N)基金属陶瓷的耐蚀性能。     

化学脱钻对硬质合金沉积金刚石薄膜的影响

采用HFCVD系统,以Cu4和H2为反应气体,分别在YG3、YG6、YG10、YG13硬质合金上沉积了金刚石薄膜,研究了化学脱钴处理对不同钴含量硬质合金沉积金刚石薄膜的影响。通过对105个样品的实验结果进行统计分析发现,YG3所得金刚石薄膜样品具有足够结合强度的比例为89％;而YG6、YG10和YG13所得样品的相应值分别为24％、7％和0％。相反,YG3、YG6、YG10和YG13所得金刚石薄膜严重破坏的比例分别为0％、64％、72％和79％。研究表明,化学腐蚀脱钴处理能够解决金刚石涂层形核率低的问题,但难以解决高钴硬质合金的附着性差的问题。     

铁镍粘结硬质合金

对Fe，Ni取代Co作为站结剂在硬质合金中的应用作了研究。实验结果表明，11．25％Fe＋3．75％Ni作为粘结剂可得到力学性能优于YG11C牌号的合金性能。本文同时对影响Fe、Ni粘结硬质合金性能的因素作了探讨。     

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.     

金属陶瓷复合材料的应用及市场分析

金属陶瓷材料是基于TiC或Ti（C,N）,以Ni-Mo为金属相的复合材料,具有高硬度、高耐磨性、红硬性以及化学稳定性,因而被广泛用作刀具材料、模具材料以及耐热、耐磨部件。文章分析了在切削刀具领域Ti（C,N）金属陶瓷刀具、硬质合金（WC-Co）刀具等所占市场份额,并分析了Ti（C,N）金属陶瓷刀具应用受限的主要原因。文章还分析了Ti（C,N）金属陶瓷复合材料在热挤压模具方面应用的可行性。     

A new family of cermets: Chemically complex but microstructurally simple

Cermets based on Ti(C,N) have interesting properties, such as high wear resistance, high chemical stability and good mechanical strength at high temperature, but to become a viable alternative to cemented carbides, the fracture toughness and damage tolerance must be significantly improved. Complete solid-solution cermets (CSCs) have been proposed to further improve the mechanical properties of these materials. However, to develop this family of cermets with a high level of quality and reliability, using pre-fabricated complex carbonitrides is necessary instead of unalloyed mixtures as the raw ceramic material. A mechanochemical process called mechanically induced self-sustaining reaction (MSR) is suitable to obtain these complex carbonitrides with high stoichiometric control. On the other hand, high entropy alloys (HEAs), which can also be obtained by mechanochemical processes, are a good candidate to replace the current binder phase in cermets because they exhibit high strength and ductility at high temperature and good resistance to both wear and corrosion. In this work, a new family of CSCs based on (Ti,Ta,Nb)C_xN_1 − x with HEAs belonging to the Fe-Co-Ni-Cr-Mn-V system as the binder phase is developed by mechanochemical processes. With only two constituent phases, these cermets have a simple microstructure but a high compositional complexity because both the ceramic and binder phases are complex solid solutions with at least five components.     

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.     

Cutting performance of titanium carbonitride cermet tools

Titanium carbonitride matrix cermets with different WC/TiCN ratio, Co/Ni ratio and C/N ratio in TiCN solid solution were prepared according to a powder metallurgical procedure. Their cutting performance was investigated, and their flank worn micrographs were observed by using scanning electron microscopy. Results show the optimum WC/TiCN ratio, Co/Ni ratio and C/N ratio are 0.30, 2.0, 1.0, respectively. Cermets with high hardness and TRS show excellent flank wear resistance. The flank wear of the tool is caused by the abrasive, oxidation and diffusive wear at high cutting speed. Decreasing Co/Ni ratio and C/N ratio improve the oxidation and diffusive wear resistance of cermet tool.     

渣浆泵过流部件用合金新材料

渣浆泵过流部件工况苛刻,延长渣浆泵过流部件的寿命成为材料工作者关注的课题。在延长使用寿命的前提下,降低贵重合金元素的用量,寻找代用的合金元素,对泵的过流件的工作表面强化可降低材料成本。渣浆泵过流部件合金新材料有高铬铸铁、超高铬铸铁、中铬铸铁、耐腐蚀合金和金属陶瓷。金属陶瓷按制备方法分为整体强化、表面处理强化,表面处理强化的手段有化学热处理、PVD气相沉积和等离子喷涂。     

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.     

Yb2O3或Y2O3掺杂Cu-(NiFe2O4-10NiO)惰性阳极的导电性和耐蚀性

在氧分压约为100 Pa的氮气氛下烧结制备了掺杂Y2O3、Yb2O3的10Cu-(NiFe2O4-10NiO)金属陶瓷,并对其进行导电性能测试和10h(Na3A1F6-Al2O3体系中)铝电解实验.采用XRD、SEM和EDS分析稀土氧化物以及其与陶瓷基体反应产物的分布,考查电解实验后材料表层显微结构变化尤其是金属相的流失情况,评价稀土氧化物的添加对金属陶瓷电解初期腐蚀行为的影响.结果表明:掺杂稀土氧化物均使NiO相呈连通迹象,掺杂Yb2O3金属陶瓷晶粒较未掺杂的粗大,其与陶瓷相反应生成物成点线状分布于NiFe2O4相晶界,Y2O3与陶瓷相反应生成物则分布于NiO与NiFe2O4相间;所制备材料具有半导体特征,随着稀土氧化物的掺杂,材料导电性呈下降趋势;掺杂稀土氧化物尤其是Yb2O3有利于提高材料的耐蚀性能.