Ceramics International 43 (2017) 368–375
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Ceramics International
journal homepage: www.elsevier.com/locate/ceramint
Tribological characteristics of conventionally sintered TiCN-WC-Ni/Co crossmark cermets against cemented carbide
Vikas Verma, B.V. Manoj Kumar
Department of Metallurgical and Materials Engineering, Indian Institute of Technology (IIT), Roorkee, India
A R T I C L E I N F O
Keywords:
TiCN
Cermets
Sliding wear
Cemented carbide
A B S T R A C T
Present research deals with the tribological behavior of TiCN-WC-Ni/Co cermets with or without TaC in unlubricated sliding at different loads (5–20 N). Commercially available cemented carbide hard material was selected as counterbody to understand the potential of new generation cermets in severe conditions of sliding. Dense TiCN based cermets were processed via conventional sintering whose hardness and fracture toughness varied from 14 to 16 GPa and 8.75–9.25 MPa m1/2, respectively. The size and fraction of adjacent ceramic phase in the microstructure influenced mechanical properties and wear behavior of the cermets. A variation of 79% in steady state coefficient of friction (COF) and 70% in wear rate is found with respect to composition and load. Hard oxide debris particles are responsible for higher COF at low load, whereas their compaction results in the tribolayer formation at high load. Material transfer from cemented carbide ball onto the cermet disc enhanced at high load due to increased contact temperature. The refined size and least fraction of adjacent ceramic phase are attributed for reduced wear in TaC added TiCN-WC-Ni/Co cermet.
1. Introduction
TiCN-based cermets are reported to possess unique properties of low density, high temperature resistance, high hardness, good tough-ness, ability to undergo plastic deformation, superior wear and corro-sion resistance, good thermal shock resistance, high strength, thermal and electrical conductivity [1–8]. The microstructures of TiCN-based cermets are typically characterized by core-rim ceramic phases at-tached strongly through the binder phase. The evolution of core- rim structure is attributed to the dissolution- reprecipitation process occurring during sintering [9,10]. As intended applications of TiCN-based cermet materials include cutting tool inserts and dies for the metal forming, a thorough understanding on their wear behavior is important. It is reported in literature that the addition of TaC to TiCN based cermets imparts strengthening effect to the cermet composite and exhibits superior performance in machining conditions. [1,4,8,12– 15]. Many researchers estimated the performance of TiCN cermet compositions in various tribological conditions. Based on the experi-mental and material parameters, the complex tribological behavior of TiCN-based cermets is widely characterized by adhesion, abrasion, tribochemical wear, oxidation, plastic deformation and/or fracture [14–21]. Extensive research has been carried out in processing TiCN based cermets to improve their mechanical and wear performance [18]. Recent research also reveals that the addition of metallic binders and
carbides results in improvement of mechanical and wear properties. Fully dense ( gt; 99%) TiCN based cermets were prepared via conven-tional sintering with the addition of Ni, Co, Ni-Co, Ni-Mo or Ni-Co-Mo as binders and WC, NbC, HfC or TaC as secondary carbides. The
hardness varied between 9 and 16 GPa and fracture toughness from 8.5 to 16 MPa m1/2. A wide range of COF values from 0.2 to 1.2 and wear
rate from 10minus;7 mm3/N m to 10minus;3 mm3/N m are reported for the TiCN-based cermets with varying cermet compositions in dry sliding condi-tions [16–21]. A summary of tribological characteristics of various TiCN-based cermets in dry sliding conditions is presented in Table 1.
It can be noted from Table 1 that the sliding wear behavior of various TiCN based cermets have been extensively studied mainly against steel ball, probably due to the application of tools in machining steel and less information is available about the behavior against hard ceramic counter body. Though difficult to compare the complete tribological behavior with the limited information and variety of sliding speed and load, the COF is observed to be at higher side for the cermets slid against Si3N ball as compared against steel ball, while no such a major change is observed in wear rate or dominant wear mechanisms. In order to assess the true potential of new generation TiCN based cermets, their tribological behavior against other hard materials is essentially required. In the present work, the addition of TaC and Ni-Co on tribological properties of TiCN-based cermets against cemented carbide counter body in unlubricated sliding wear conditions is
Corresponding author.
E-mail addresses: manojfmt@iitr.ac.in, manojpatruni@gmail.com (B.V. Manoj Kumar).
http://dx.doi.org/10.1016/j.ceramint.2016.09.167
Received 18 July 2016; Received in revised form 22 September 2016; Accepted 23 September 2016
Available online 24 September 2016
0272-8842/ copy; 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved.
V. Verma, B.V. Man
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陶瓷国际43(2017)368-375
常规烧结TiCN-WC-Ni / Co金属陶瓷对硬质合金的摩擦学特性
维卡斯维尔马,马诺伊·库马尔
印度理工大学冶金和材料工程系(IIT),印度Roorkee
关键词:
TiCN 金属陶瓷 滑动磨损 硬质合金
摘要:
目前的研究涉及具有或不具有TaC的TiCN-WC-Ni / Co金属陶瓷在不同载荷(5-20 N)下的非润滑滑动中的摩擦学行为。选择市售的硬质合金硬质材料作为对抗体,以了解新一代金属陶瓷在严重滑动条件下的潜力。通过常规烧结法处理密集的TiCN基金属陶瓷,其硬度和断裂韧性分别为14至16 GPa和8.75-9.25 MPa m 1/2。微观结构中相邻陶瓷相的尺寸和分数影响金属陶瓷的机械性能和磨损行为。在组成和载荷方面,发现稳态摩擦系数(COF)为79%,磨损率为70%。硬氧化物碎片颗粒负责低负荷下的较高COF,而它们的压实导致高负载下的三层形成。由于接触温度的升高,从硬质合金球到金属陶瓷盘的材料转移在高负载下增强。相邻陶瓷相的精细尺寸和最小部分归因于在TaC添加的TiCN-WC-Ni / Co金属陶瓷中的磨损降低。
- 介绍
据报道,TiCN基金属陶瓷具有低密度,耐高温,高硬度,良好韧性,经受塑性变形的能力,优异的耐磨性和耐腐蚀性,良好的耐热冲击性,高强度和耐热性等特性。 电导率[1-8]。TiCN基金属陶瓷的微观结构通常特征在于通过粘结相强烈渗透的核心 - 陶瓷相。核心结构的演化归因于烧结过程中发生的溶解 - 再沉淀过程[9,10]。由于TiCN基金属陶瓷材料的预期用途包括切割工具插件和用于标准成形的模具,对其磨损行为的透彻了解至关重要。据文献报道,添加TaC至TiCN对金属陶瓷复合材料施加强化作用,在加工条件上表现出优异的性能。 [1,4,8,12-15]。许多研究人员估计TiCN金属陶瓷组合物在各种摩擦学条件下的性能。基于实验和材料参数,TiCN基金属陶瓷的复杂摩擦学行为被广泛地表征为粘附,磨损,摩擦化学磨损,氧化,塑性变形和/或断裂[14-21]。在加工TiCN基金属陶瓷方面进行了广泛的研究,以提高其机械和磨损性能[18]。最近的研究还表明,金属粘合剂和碳化物的添加导致机械和磨损性能的提高。通过常规烧结制备全密度(gt; 99%)TiCN基金属陶瓷,添加Ni,Co,Ni-Co, 作为粘合剂的Ni-Mo或Ni-Co-Mo,作为二次碳化物的WC,NbC,HfC或TaC。 硬度在9GPa至16GPa之间变化,断裂韧性为8.5至16 MPa m 1/2。 对于在干滑动条件下具有不同金属陶瓷组成的TiCN基金属陶瓷,报道了宽范围的COF值为0.2至1.2,磨损率为10 -7 mm 3 / N m至10 -3 mm 3 / N m [16-21]。 各种TiCN基金属陶瓷在干滑动条件下的摩擦学特征的总结如表1所示。
从表1可以看出,各种TiCN基金属陶瓷的滑动磨损行为主要针对钢球进行了广泛的研究,这可能是由于在加工钢中应用了刀具,而且对于硬陶瓷对体的行为信息较少。尽管难以将完整性行为与有限的信息和滑动速度和载荷的多样性进行比较,但相对于钢球来说,COF观察到在较高的一侧为金属陶瓷滑动Si 3 N球,而没有这样的主要变化观察磨损率或主要磨损机制。为了评估新一代TiCN基金属陶瓷的真正潜力,它们对其他硬质材料的摩擦学行为基本上是必需的。在本工作中,系统地研究了TiC和Ni-Co在非润滑滑动磨损条件下对TiCN基金属陶瓷对硬质合金对体的摩擦学性能的添加。选择硬质合金硬质材料作为对抗体,以了解新一代金属陶瓷在严重滑动条件下的潜力。磨损机理在金属陶瓷组成和滑动载荷方面进行了特别的阐述。
表格1
在干燥(空气)条件下滑动期间TiCN基金属陶瓷对不同反应物的摩擦学特征的总结
金属陶瓷组成 |
相对体 |
干燥(空气中)滑动磨损试验条件 |
COF |
磨损率(mm 3 / N m) |
主导磨损机制 |
参考 |
TiCN–20Ni)- WC/NbC/ TaC/HfC |
钢 |
300 rpm; 5,20或50 N |
0.4–0.7 |
10minus;6–10minus;7 |
三层剥离 |
[11] |
TiC–NiMo |
钢 |
2.2 m/s; 40 N |
0.2–0.3 |
3.8times;10minus;7–13 times;10minus;7 |
三层剥离 |
[16] |
(WC-Co)–TiC, TaC/NbC |
钢 |
1500-3000r/min; 40 N-350 N |
0.2–0.7 |
-- |
摩擦膜去除 |
[20] |
TiCN–Ni-WC |
钢 |
5米时0.1m/s; 20或50 N |
0.27–0.73 |
2.7times;10minus;7–3.4times;10minus;6 |
薄三层除去和分层 |
[21] |
TiCN–Ni–Mo |
Si 3 N 4 |
0.5 m/s; 5 N |
0.8 |
10minus;7 |
断裂 |
[19] |
TiCN–Al 2 O 3 –Ni–Mo |
Si 3 N 4 |
0.5 m/s; 5 N |
1.0 |
10minus;7 |
三层剥离 |
[19] |
(TiCN-Ni-WC)Co/TaC |
硬质合金 |
500 rpm; 5, 10或 20 N |
0.23–1.1 |
(2.2–7.3)times;10minus;7 |
磨损和三层剥离 |
图1(a)烧结Ti(CN)-5WC-20Ni-5TaC金属陶瓷的SEM图像。 金属陶瓷的核心,边缘和粘合剂相的EDS分析分别在(b),(c)和(d)中示出
2实验设置
2.1。 TiCN基金属陶瓷的加工和表征按市售的粉末:TiCN(1-2mu;m,Sigma Aldrich,USA),WC(2mu;m,Sigma Aldrich,USA),TaC(lt;5mu;m,Sigma Aldrich,USA),Ni (100目筛网,新德里中央药房(CDH))和Co(3-5mu;m,金属粉末有限公司(MEPCO)
使用TiCN(CN)-5WC-20Ni,Ti(CN)-5WC-20Ni-5TaC,Ti(CN)-5WC-10Ni-10Co,Ti (CN)-5WC-10Ni-10Co-5TaC。粉末使用高能球磨机(PM100,Retsch,德国)在氧化锆小瓶中以250rpm混合8小时,氧化锆球与粉末的比例为10:1。将混合粉末在100MPa下压实,并且在1550℃温度下在卧式管式炉(Naskar&Company,India)中在21mm直径和5-6mm厚度的盘中随后在流动氩气中保持2小时保持时间 烧结金属陶瓷盘的厚度在3和5mm之间变化。 使用嵌有9,6,3或1mu;m大小的磨料颗粒的砂纸打磨烧结盘。 使用扫描电子显微镜(SEM)和能量分散光谱(EDS)进行微结构表征。
通常,所有金属陶瓷的SEM(BSE)图像显示出三个主要的显微组织相,其对比度有明显的差异。Ti(CN)-5WC-20Ni-5TaC的三个主相的典型EDS分析如图1所示。 EDS分析表明,黑核相为TiCN,灰边相为(Ti,W,Ta)CN的固溶体,亮连续相主要由Ni的粘结相组成。 作为烧结过程中溶解和再沉淀的结果,提出了芯 - 边缘形态的形成[6]。
通过线性截距法对每个金属陶瓷微观结构进一步评估微观结构参数。 确定N陶瓷/陶瓷晶界和N陶瓷/粘合剂界面的每单位长度的平均拦截数,并用于估计陶瓷颗粒的邻接性(C)和粘结相的平均自由程(lambda;) 根据以下关系:
C = 2Nceramic / ceramic /[2Nceramic/ ceramic Nceramic / binder ] (1)
lambda; = Oslash;ceramic /Nceramic / binder (2)
其中陶瓷是平均陶瓷粒径。
测量陶瓷邻接性和粘合剂平均自由程,以研究微结构对金属陶瓷机械性能的影响。 图。 图2(A)表示Ti(CN)-5WC-10Ni-10Co-5TaC金属陶瓷的典型SEM(BSE)图像, 图2(B)显示了所研究的金属陶瓷的陶瓷结构和粘合剂平均自由程。 陶瓷邻接性和粘结剂平均自由程分别为0.41〜0.45mu;m和1.00-1.25mu;m。 Ti(CN)-5WC-10Ni-10Co-5TaC金属陶瓷在所有研究的金属陶瓷中具有最小的陶瓷邻接性和最长的粘合剂平均自由程。
烧结金属陶瓷的硬度和断裂韧性通过维氏压痕10 kg估计15 s。 Shetty公式用于估算断裂韧性[2]。 随着金属陶瓷组成的变化,硬度从14到16 GPa变化,断裂韧性从8.75到12.5 MPa m 1/2。 使用镍和钴或镍,钴和TaC制备的金属陶瓷导致更高的硬度和断裂韧性。 对于Ti(CN)-5WC-10Ni-10Co-5TaC金属陶瓷,发现最大硬度为16GPa,最大断裂韧性为9.25MPa m 1/2的组合
2.2滑动磨损试验
使用圆珠磨损试验机(TR-210 ME,DUCOM,印度)对抛光的TiCN基金属陶瓷样品进行滑动试验。商业上可获得的硬质合金球(表面粗糙度(Ra)0.02mu;m,硬度:17GPa) 直径为10mm的用作反体。 滑动试验在无润滑环境条件(25plusmn;5℃和30-35%RH)下以500rpm(线速度0.261m / s)进行40分钟(总滑动距离626mu;m),5N,10 分别产生最大(初始)赫兹接触应力1.15,1.45或1.82GPa的N或20N载荷。 在测试期间估计摩擦系数(COF),而使用触针表面轮廓仪测量在金属陶瓷盘上形成的瘢痕的宽度和深度。 使用SEM测量球表面的印模尺寸。考虑到磨损痕迹平均5个读数。 按照以下公式计算金属陶瓷盘和球的磨损体积(mm3):
Wear volume of ball = prod; times; (wear scar dimension average value)4 /
(64 times; radius of ball)
根据滑动距离和载荷标准化的磨损体积计算出比磨损率(mm3 / N m)。 进行滑动试验4-5次,报告了摩擦磨损的平均值。 通过使用磨损金属陶瓷盘和磨损硬质合金球的表面的SEM-EDS分析来鉴定主要的磨损机理。
3。结果与讨论
3.1。 摩擦行为
图1中的Ti(CN)-5WC-20Ni金属陶瓷的典型COF图作为时间的函数。并且所研究的金属陶瓷的平均稳态COF值显示为表2中的滑动负载的函数。随着金属陶瓷组合物或滑动载荷的变化,平均稳态COF从0.25变化到1.1。滑动硬质合金球导致粗糙表面的形成,这增加摩擦并导致较高的COF值。在组成和载荷方面发现稳态摩擦系数(COF)为79%的变化。对于TiCN基金属陶瓷,当先前有不同金属陶瓷组成和滑动条件的研究人员对钢球进行滑动时,报告的COF值从0.2降低到了。[16-21]。在给定载荷下,Ti(CN)-5WC-20Ni金属陶瓷表现出较高的COF值,Ti(CN)-5WC-10Ni-10Co-5TaC的COF值较低,而COF随着载荷的增加而降低,从5〜20N任何金属陶瓷因此,研究
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