原位TiC弥散强化420不锈钢的显微组织与耐磨性研究

采用原位铸造法和电渣重熔工艺制备了TiC颗粒弥散强化420不锈钢材料,并用环-块摩擦磨损试验机研究了油润滑下弥散强化钢的滑动摩擦磨损性能.结果表明:原位TiC颗粒均匀弥散分布在基体中,颗粒尺寸为1～5 μm,呈四边形或多边形,与基体结合良好且无团聚现象.在420不锈钢中原位合成TiC颗粒后室温强度明显提高,但420不锈钢的塑性和冲击韧性下降;与420基体磨损试验对比可见,TiC弥散强化420不锈钢具有良好的耐磨性.     

TiC颗粒弥散强化不同基体钢的磨损性能研究

运用原位合成工艺制备出TiC颗粒弥散强化不同基体的钢种,TiC颗粒在强化钢中分布均匀。结果表明:钢中合金元素越多,TiC与基体的结合强度越低,室温强度提高幅度越小。TiC颗粒能够提高低合金钢的磨损性能。但是,高合金钢中的TiC颗粒容易剥落成为磨粒从而恶化磨损性能。     

TiC对激光熔覆H13-TiC复合涂层组织和性能的影响

为提高热作模具钢的表面性能,在H13钢表面激光熔覆制备了H13-TiC复合涂层,研究了添加不同含量的TiC对H13-TiC复合涂层显微组织的影响,并模拟H13工况,测试了复合涂层的热稳定性、摩擦磨损性能等.结果表明,TiC含量较低时呈现近圆形、菱形等不规则形状;随着TiC含量的提高,呈现棒状、枝晶状等形态;TiC强化相的添加有效提高了材料的热稳定性、耐磨性能,熔覆层的耐磨性比H13基体提高3.5倍.这是TiC陶瓷颗粒在熔覆层中弥散和细晶强化共同作用的结果.     

TiC弥散强化17-4PH钢的显微组织和性能

采用熔铸过程中的原位反应合成工艺方法,制备了TiC弥散强化17-4PH。实验结果表明,弥散强化钢中的TiC呈球状形貌,且分布均匀,没有出现团聚现象;颗粒尺寸为3-5μm。在17-4PH不锈钢基中引入TiC颗粒后,看不到明显的马氏体,而且在奥氏体晶界上发现有δ铁素体条存在。在油润滑条件下,弥散强化钢的耐磨损性能比基体合金高3倍。     

TiC对铁基合金喷焊层组织与性能影响

目的研究不同TiC添加量对铁基合金喷焊层组织与性能的影响。方法采用等离子喷焊技术在Q235表面制备了铁基合金喷焊层,借助X射线衍射分析、金相显微镜、显微硬度计以及磨粒磨损试验设备,分别对喷焊层的物相、显微组织、显微硬度、耐磨性能进行测试。结果未添加TiC的喷焊层主要由马氏体、奥氏体、(Fe,Cr)_7C_3、(Fe,Ni)固溶体等物相组成,加入不同含量的TiC后,出现了TiC、TiB_2等新物相,但各试样的衍射强度均存在相应程度的降低,某些区域的衍射峰甚至消失。随着TiC含量的增加,喷焊层的硬度和耐磨性增加,但硬度和耐磨性能在TiC添加量达到一定程度(w_(TiC)3.0%)时反而降低。当TiC添加量为3%时,喷焊层的组织致密,晶粒细化,TiC弥散分布,其颗粒对喷焊层组织产生了弥散强化和细晶强化作用;显微硬度可达843HV_(0.5),较未添加TiC喷焊层提高了约300HV_(0.5),其相对耐磨性较Q235钢提高了约12倍,显微硬度与耐磨性得到显著提高。结论添加适量的TiC颗粒,可使金属基体与硬质相达到良好匹配,从而确保了喷焊层的高硬度和良好的耐磨性能。     

埋弧堆焊TiC颗粒增强复合涂层的组织与性能

以TiFe粉、Cr粉、Ni粉、Fe粉、胶体石墨等为原料,利用合金粉粒埋弧堆焊技术在Q235钢表面原位反应合成TiC颗粒增强Fe基复合涂层。利用SEM,XRD和EDS等分析了涂层的显微组织,并在室温干滑动磨损条件下测试该涂层的耐磨性能。结果表明:利用合金粉粒埋弧堆焊技术,可以原位合成粒径在2μm以下、弥散分布的TiC颗粒。涂层组织由TiC颗粒、马氏体和奥氏体构成。涂层平均显微硬度达601HV0.2,约是碳钢基体的3倍。由于TiC颗粒和马氏体的抗磨损性能使涂层具有优异的耐磨性能,因此涂层磨损质量约是基体金属的1/10。埋弧堆焊双层涂层与单层涂层相比,马氏体含量减少,奥氏体和TiC含量增加,耐磨性更好。     

TiC颗粒增强低合金铁素体钢的耐磨性能

通过与传统低合金铁素体钢做对比,研究了原位合成方法制备的1.0vol%TiC颗粒增强型铁素体耐磨钢的磨粒磨损性能。采用光学显微镜(OM)、扫描电镜(SEM)及能谱分析(EDS)对试验钢的显微组织形貌和析出相粒子分布进行了分析,并对试验钢的硬度、强度、韧塑性和磨粒磨损性能进行测试。试验结果表明: 经过轧制后的TiC粒子在试验钢中分布均匀,其中纳米TiC粒子产生明显的沉淀强化作用,提高了基体的强度和硬度,并保证了良好的弯曲性能。粒径1～5 μm的TiC颗粒有效阻碍了磨粒对基体的犁削作用,提高了基体抵抗磨粒磨损的能力,TiC增强后的铁素体试验钢磨损量仅为未增强铁素体钢的60%,与未增强铁素体钢淬火+低温回火处理后的耐磨性相当。TiC颗粒增强铁素体钢的磨粒磨损机制既包括犁皱塑性变形机制又包括显微切削机制,钢的耐磨性提高为纳米、微米TiC粒子共同作用的结果。     

35CrMnSi 表面氩弧熔覆原位自 生 TiC 复合涂层的组织及耐磨性

目的提高截齿的耐磨性,延长其使用寿命。方法利用氩弧熔覆技术在35CrMnSi钢表面制备TiC增强镍基复合涂层,分析涂层的显微组织和物相组成,测试涂层在室温下的显微硬度和耐磨性,并分析磨损机制。结果氩弧熔覆涂层的显微组织致密均匀,涂层与基体呈冶金结合,主要由TiC,γ-Ni,M23C6等物相组成。TiC颗粒呈块状,尺寸为1~2μm,弥散分布在涂层中。涂层硬度和耐磨性与(Ti+C)含量有关,熔覆粉末中(Ti+C)质量分数为20%时,涂层最高硬度可达1190HV,耐磨性达到基体的7.5倍。结论熔覆涂层的显微硬度较基体有显著提高。在室温冲击载荷作用下,熔覆涂层的主要磨损机制为显微切削磨损,可大大提高基体材料的耐磨性能。     

激光熔覆TiC增强不锈钢涂层的组织及性能

以机械混合后的2205不锈钢、钛铁和Cr3C2粉末为原料,在16Mn钢的表面制备了TiC增强不锈钢激光熔覆层,并对其显微组织、摩擦磨损及电化学腐蚀行为进行了研究。结果表明:熔覆层组织主要由α-Fe、γ-Fe和TiC析出相构成,Ti和C元素反应充分,无Cr_3C_2陶瓷相残留,也无其他杂相生成;随TiC比例的增加,γ-Fe相含量减少,TiC析出形貌由尺寸较小的块状转变为尺寸相对较大的十字放射状; TiC强化相的引入有效地提高了熔覆层的显微硬度和耐磨性,且降低了熔覆层粘着磨损的倾向,并增强了其抗磨粒磨损的能力;相比于单一2205不锈钢熔覆层,TiC强化不锈钢熔覆层在3.5%NaCl水溶液中的钝化能力下降,但同步补充Cr元素能够有效改善其耐腐蚀性能。     

TiC颗粒增强钢基表面复合材料的制备

采用Ti—C-Al-Ni系SHS熔铸制备Tic颗粒增强钢基表面复合材料，研究了其组织和耐磨性。结果表明：用SHS熔铸法制备的钢基表面复合材料强化相和基体结合良好；表层TiC颗粒分布密集，颗粒均匀圆整，粒度为1～2μm；表面硬度HV高达950，且硬度由表层向基体呈梯度分布；磨损时密集的高硬度的细小圆球状TiC颗粒大大降低了磨损率；耐磨性比基体提高5．6倍。     

等离子熔敷TiC/γ-(Fe,Ni)复合涂层组织与耐磨性

为了提高奥氏体不锈钢的耐磨性能,扩大其应用范围,以Ti-C-Fe-Ni混合合金粉末为原料,利用等离子熔敷技术在1Cr18Ni9Ti奥氏体不锈钢表面原位合成了TiC增强耐磨复合涂层。分析了涂层的显微组织结构,测试了涂层沿层深方向的硬度分布,评价了涂层在室温干滑动磨损试验条件下的摩擦磨损性能,结果表明:等离子熔敷TiC金属陶瓷增强复合涂层显微组织细小均匀,由花瓣状和少量颗粒状TiC初生相均匀分布在TiC/γ-(Fe,Ni)共晶基体上组成,涂层与不锈钢基材之间形成了完全冶金结合,涂层平均显微硬度约790 HV,涂层在室温干滑动磨损试验条件下表现出良好的耐磨性及较低的摩擦系数。     

钢表面离子束改性类金刚石膜层性能

离子束沉积类金刚石膜是钢表面改性的一项新技术。类金刚石改性膜层显微硬度和表面电阻率在特定轰击能量下出现峰值 ;双离子束轰击混合界面可以提高膜层显微硬度 ,并使峰值向低能量方向偏移 ,而且大大增强膜基结合强度。在大气环境中 ,改性膜层对钢的摩擦系数达到 0 0 80～ 0 1 80 ,在摩擦过程中起减摩作用。另一方面 ,类金刚石膜层显著提高钢的耐磨性 ,试验表明 ,40Cr钢表面镀膜后其磨损量是镀膜前的 1 /2 74。类金刚石膜由于使 2Cr1 3不锈钢在 3 5%NaCl溶液中的自然电位Ecorr和点蚀击穿电位Eb 增大 ,因而明显增强钢的抗点蚀能力。     

不锈钢等离子渗铪并固体渗碳后的高温摩擦性能

目的提高0Cr18Ni9Ti奥氏体不锈钢的抗高温摩擦性能。方法利用等离子渗金属技术在不锈钢表面等离子渗铪,之后进行固体渗碳,在HT-500型球-盘磨损试验机上进行高温摩擦磨损实验,分析其高温摩擦性能及摩擦机制,并与不锈钢基体试样及不锈钢渗铪试样进行对比。结果渗铪试样的渗层厚度约为45μm,渗铪+渗碳试样的渗层厚度达100μm。渗铪+渗碳层弥散分布着许多粒状和短棒状碳化物颗粒,碳化物类型主要为MC型、M7C3型和M23C6型。基材的摩擦曲线波动起伏大;渗铪试样的摩擦系数较大,但磨损微观表现平稳;渗铪+渗碳试样的摩擦系数最小。磨损失重由大到小依次为:基材渗铪试样渗铪+渗碳试样。在300,500℃下,渗铪试样的耐磨性相对基材分别提高至1.47倍和1.94倍,渗铪+渗碳试样分别提高至2.13和2.28倍。基材划痕尺寸宽且较深;渗铪试样的表面硬度提高,且摩擦磨损过程中出现了合金氧化物;渗铪+渗碳试样的表面硬度高,基体韧性好,仅出现了很浅且窄的磨痕。结论通过等离子渗铪及离子渗铪+固体渗碳,均能提高不锈钢表面的抗高温摩擦性能,相比之下,离子渗铪+固体渗碳的效果更好。     

WC-(W,Cr)_2C-Ni/Ag复合涂层的制备及摩擦学性能

针对众多运动部件存在严重的摩擦磨损问题,使用大气等离子喷涂(APS)设备在1Cr18Ni9Ti不锈钢金属基材上喷涂制备WC-(W,Cr)2C-Ni和WC-(W,Cr)2C-Ni/Ag两种防护涂层,使用CSM摩擦磨损试验机考察两种涂层在室温下与Si3N4球配副时的滑动摩擦磨损性能。结果表明:Ag相的添加可明显降低涂层在干摩擦条件下的摩擦因数,并能减轻涂层的磨损程度;APS制备的WC-(W,Cr)2C-Ni/Ag复合涂层不仅具有优良的自润滑性能,而且具有极佳的耐磨性能,有望作为一种新型耐磨自润滑涂层材料。     

Tribological properties of TiC-Fe coatings obtained by plasma spraying reactive powders

Titanium carbide-based coatings have been considered for use in sliding wear resistance applications. Carbides embedded in a metal matrix would improve wear properties, providing a noncontinuous ceramic surface. TiC-Fe coatings obtained by plasma spraying of spray-dried TiC-Fe composite powders containing large and angular TiC particles are not expected to be as resistant as those containing TiC particles formed upon spraying. Coatings containing 60 vol% TiC dispersed in a steel matrix deposited by plasma spraying reactive micropellets, sintered reactive micropellets, and spray-dried TiC-Fe composite powders are compared. The sliding wear resistance of these coatings against steel was measured following the test procedure recommended by the Versailles Advanced Materials and Standards (VAMAS) program, and the inherent surface porosity was evaluated by image analysis. Results show that, after a 1-km sliding distance, TiC-Fe coatings obtained after spraying sintered reactive powders exhibit scar ring three times less deep than sprayed coatings using spray-dried TiC-Fe composite powders. For all coatings considered, porosity is detrimental to wear performance, because it generally lowers the coating strength and provides cavities that favor the adhesion of metal. However, porosity can have a beneficial effect by entrapping debris, thus reducing friction. The good wear behavior of TiC-Fe coatings manufactured by plasma spraying of sintered reactive powders is related to their low coefficient of friction against steel. This is due to the microstructure of these coatings, which consists of 0.3 to 1 μm TiC rounded particles embedded in a steel matrix. Presented at the International Conference on Metallurgical Coatings and Thin Films, ICMCTF-92, Apr 6–10, 1992, San Diego.     

Effect of TiC particles on the oxidation behavior of 2Cr13 stainless steel in a simulated marine environment at 550°C

In this study, the oxidation behavior of 2Cr13 stainless steels with/without TiC particles was investigated in a simulated marine environment at 550°C. The results showed that TiC particles greatly accelerated the oxidation rate of 2Cr13 steel during the cyclic oxidation reaction. At the same time, the effect of acceleration was alleviated by the small size and uniform distribution of TiC particles. As galvanic corrosion in the vicinity of TiC particles occurred in 3.5% NaCl solution spray, more NaCl particles deposited on the alloy surface, especially in the area around TiC particles. At 550°C, some shell-like oxidation products were generated on the 2Cr13 steel surface due to TiC addition, and then the porous oxidation products provided poor protective ability. Besides, the defect and stress in the oxide scale was reduced due to the small size and uniform distribution of TiC particles in 2Cr13 steel.     

电渣重熔对TiC强化2Cr13不锈钢力学性能和断口的影响

在2Cr13不锈钢中引入TiC颗粒后,室温强度有大幅提高,但塑性和冲击韧性却发生了较大幅度的下降．原位合成的TiC颗粒,尺寸较大且有轻微团聚现象,导致了在拉伸和冲击过程中颗粒易破碎,断裂机制是以TiC增强体失效为主;对TiC强化2Cr13进行电渣重熔后,综合性能得到了改善,TiC颗粒变小且分布变均匀,在拉伸和冲击过程中颗粒不易破碎,断裂机制是以TiC与基体的界面失效为主．     

Sliding abrasive wear characteristic of TIG cladded TiC reinforced Inconel825 composite coating

TiC reinforced Inconel 825 alloy matrix composite coating with different weight percentage (20, 40, and 60) of TiC has been produced by TIG cladding process. With the increase in TiC percentage in the produced coating a drastic alteration in the coating morphology perceived predominantly due to the degree of melting of pre-deposited TiC particles. The sliding abrasive wear measured through the height loss of the coated pin extracted from the TiC-Inconel825 composite coatings executed against alumina abrasive wheel show the effect of TiC percentage as well as the sliding velocity during the test. The worn surfaces characterized by SEM suggested that the abrasion wear is predominant for removal of the coating along with delamination through oxidation. The coefficient of friction of the coating assessed against harden steel plate (HRC58) indicated a gradual reduction from 0.71 to 0.60 with the increase in TiC content in the TiC-Inconel825 composite coating.     

TiC-Maraging stainless steel composite： microstructure, mechanical and wear properties

Particulate TiC reinforced 17-4PH and 465 maraging stainless steel matrix composites were processed by conventional powder metallurgy （P/M）. TiC-maraging stainless steel composites with theoretical density 〉97% were produced using conventional P/M. The microstructure, and mechanical and wear properties of the composites were evaluated. The microstructure of the composites consisted of （core-rim structure） spherical and semi-spherical TiC particles depending on the wettability of the matrix with TiC particles. In TiC-maraging stainless steel composites, 465 stainless steel binder phase showed good wettability with TiC particles. Some microcracks appeared in the composites, indicating the presence of tensile stresses in the composites produced during sintering. The typical properties, hardness, and bend strength were reported for the composites. After heat treatment and aging, an increase in hardness was observed. The increase in hardness was at- tributed to the aging reaction in maraging stainless steel. The specific wear behavior of the composites strongly depends on the content of TiC particles and their interparticle spacing, and on the heat treatment of the maraging stainless steel.