Effects of nano-Al_2O_3 and nano-ZrO_2 on the microstructure, behavior and abrasive wear resistance of WC-8Co cemented carbide

WC-8wt.% Co cemented carbides with varied nano-Al 2 O 3 and nano-ZrO 2 contents were prepared respectively following conventional powder metallurgical procedures. Effects of nano-Al 2 O 3 and nano-ZrO 2 on the microstructure, behavior, and abrasive wear resistance were investigated. The result shows that a finer and more homogenous microstructure can be achieved by increasing nano-Al 2 O 3 , and increasing nano-ZrO 2 makes the microstructure more refined. Nano-Al 2 O 3 and nano-ZrO 2 could both help to give increased hardness. Transverse rupture strength is higher if the above nano-oxides are doped appropriately, whereas excess addition is deleterious. Abrasive wear resistance presents different variations with respect to increasing nano-Al 2 O 3 and nano-ZrO 2 . By contrast, increasing nano-ZrO 2 enhances the abrasive wear resistance more effectively than increasing nano-Al 2 O 3 . The influence of the two nano-oxides contents on the abrasive wear resistance does not almost vary with wear time, and the optimum addition level of nano-Al 2 O 3 in WC-8% Co cemented carbide is 0.3 wt.% from the stand of abrasive wear resistance. In addition, both of the nano-oxides can retard the increase of wear rate in long-term abrasive wear.

Development of functionally graded aluminium composites using centrifugal casting and influence of reinforcements on mechanical and wear properties

Functionally graded Al/B_4C, Al/Si C, Al/Al_2O_3 and Al/TiB_2 composites with constant 12%(mass fraction) of reinforcement were fabricated by centrifugal casting and hollow cylindrical components were obtained. Microstructural characteristics were investigated at outer surface of all composites and segregation of reinforcement particles was observed. Graded property of the composites with different reinforcements was investigated through hardness and tensile measurements. Results revealed that the outer peripheries of all composites exhibit higher hardness except in Al/B_4C composite and the outer zones of all composites show higher tensile strength. Abrasive wear test was conducted on the outer peripheries of all composites and Al/TiB_2 composite exhibits less wear rate.

AISI 300系列奥氏体不锈钢渗氮层组织和性能研究

目的在AISI 300系列奥氏体不锈钢表面制备单一S相渗氮层,提高该系列不锈钢渗氮层的硬度、抗磨损性能,对比揭示渗氮前后不锈钢的磨损机制。方法采用低温辉光等离子渗氮技术(LTPNT)在AISI 300系列奥氏体不锈钢表面制备渗氮层。利用光学显微镜(OM)、扫描电子显微镜(SEM)、电子探针(EPMA)、X射线衍射仪(XRD)分析渗氮层的截面形貌、元素分布和物相组成;通过比磨损率和磨痕形貌分析渗氮层的摩擦学性能;利用电化学实验考察渗氮前后3种不锈钢的耐蚀性。结果AISI 300系列奥氏体不锈钢经380℃、12 h处理后,其表面获得了厚度为15μm左右、与基体致密结合、组织成分均匀的渗氮层;渗氮层的相结构主要为S相,无CrN相析出;经渗氮后,该系列不锈钢表面硬度均为1100HV左右,较基体硬度提高了5倍左右;不锈钢基体的磨损机理为黏着和磨粒磨损,经渗氮后转变为氧化磨损和微切削;渗氮层的比磨损率约为不锈钢基体的1/20,抗磨损的能力得到显著提升;在25℃环境温度下渗氮后,304L、316L和321的自腐蚀电位下降,腐蚀电流密度增加,腐蚀速率加快,耐腐蚀性能稍有降低。通过对比腐蚀形貌发现,渗氮层仍具有一定的耐蚀性能。结论通过LTPNT可以获得高硬度、组织均匀致密、结合强度高的渗氮层,渗氮层中S相的存在可以显著提高AISI300系列奥氏体不锈钢的表面硬度、抗磨损能力,降低其摩擦因数和比磨损率,对延长不锈钢的服役寿命有着积极的作用。

Effect of Graphite Content and Granularity on Mechanical and Tribological Properties of Bronze Alloyed Powder Composite

The bronze alloyed powder composite containing nanoparticles was developed by hot pressing.The effects of the content and granularity of graphite on hardness,machinability,bending strength,compression strength,and friction and wear behavior of the composites were studied.The microstructures of the specimens were analyzed by SEM.The results showed that the graphites are distributed in net when nanographites are added,resulting in the decrease of mechanical properties and abrasive resistance.When the content of nanographite is 10%,the composite is brittle.The graphite is distributed in the form of block when micrographite is added,improving the mechanical properties and abrasive resistance.Wear track was studied by SEM.

Slurry wear characteristics of zinc-based alloys： Effects of sand content of slurry, silicon addition to alloy system and traversal distance

这调查处理在泥浆上与标本和泥浆作文以及遍历距离的效果相关的观察穿基于锌的合金的反应。合金的作文被把 4% 硅加到它改变。泥浆作文通过在被推迟在的 060% 的范围改变沙粒子的集中被改变(液体) 电解质。电解质包含了集中的硫的酸在水的 10 L 溶解了的 4 g 钠氯化物和 5 mL。泥浆穿测试在 15500 km 的遍历距离范围上以 7.02 m/s 的速度被进行。wear 率开始与遍历距离增加了，达到了最大值并且不管标本和测试环境，此后减少了。然而， wear 率山峰比液体唯一的媒介在加沙环境的液体是不太突出的。进一步，在液体唯一的媒介的 wear 率山峰在包含泥浆的沙比那座出现在更短的遍历距离。到电解质的沙粒子的增加把样品的 wear 率归结为取决于泥浆的沙集中的 5%15% 。而且，中介(40%) 沙内容导致了最大值穿率什么时候与相比在加沙媒介的液体。然而，这最大值是静止的不到在里面液体唯一的媒介。包含更高受不了的合金的硅比当在液体唯一的媒介测试了时，免费合金取样的硅穿率。相反，而混合回答在包含 60% 沙的泥浆被注意，趋势加 20% 和 40% 沙环境在液体逆行。在后者盒子中，当一个相反的趋势在更长的遍历距离被观察时，硅的存在开始证明有害。样品的 wear 反应在试验性的条件的一个给定的集合以他们象硅和占优势的材料移动机制一样的 microconstituents 的特定的特征被讨论。合金的观察行为也通过他们的影响表面和表面下的区域的特征进一步被证实。

ZG36SiCrMnMoCuB碳化钨颗粒增强梯度复合材料

采用液态金属环瀑悬铸填充调配法成功地制出具有明显宏观组织梯度与性能梯度的ＷＣ颗粒增强新型钢基耐磨梯度复合材料，并探讨了新材料组织梯度的形成机理。试验结果表明，新材料一侧具有高硬度（ＨＲＣ６４．５），另一侧具有较高的韧性（αｋ＝７２．３Ｊ／ｃｍ２），整个断面上组织与性能是连续梯度渐变的。

ZG35CrMn2Si2Mo贝氏体铸钢组织和性能的研究

研究空冷耐磨ZG3 5CrMn2Si2Mo贝氏体铸钢的组织和性能 ,结果表明 :正火、低温回火后组织由贝氏体铁素体 (BF)和奥氏体 (AR)组成 ,具有良好的强韧性配合。分析ZG3 5CrMn2Si2Mo贝氏体铸钢的磨料磨损性能 ,并与耐磨钢ZGMn13CrMo进行比较 ,说明该贝氏体耐磨钢具有良好的耐磨性。ZG3 5CrMn2Si2Mo贝氏体铸钢作为一种新的贝氏体类抗磨材料 。

SHS反应火焰喷涂TiC-TiB_2梯度过渡陶瓷涂层摩擦磨损机理研究

以Ti-B4C-C为主反应体系,Ni-Al金属粉末为过渡材料,采用自蔓延高温合成反应火焰喷涂技术,在45钢基表面制备TiC-TiB2梯度过渡复相陶瓷涂层。对涂层进行摩擦磨损试验,利用扫描电镜观察陶瓷涂层的磨损表面形貌,并分析其摩擦机制得出:涂层的耐磨性呈梯度变化;在不同的摩擦层面存在着粘着磨损、磨粒磨损、疲劳磨损等多种不同的磨损机理。

漆籽壳纤维(LSSF)增强HDPE/UHMWPE复合材料摩擦学性能

大多数水泵失效都是由于水泵导轴承的磨损毁坏而引起的,而水泵在含泥沙水体中的应用加重了水泵导轴承的磨损程度,因此,研制一种新的自润滑耐磨复合材料来代替传统金属材料用于水泵导轴承制造是一种趋势。以高密度聚乙烯(HDPE)、超高分子量聚乙烯(UHMWPE)为基体,漆籽壳纤维(LSSF)为填料,通过熔融共混、注射成型制备了LSSF/HDPE/UHMWPE复合材料,研究了复合材料的流动性和摩擦学性能。研究结果发现,LSSF能提高复合材料的熔体流动速率,并随着LSSF含量的增加而增加,当添加的纤维含量为20%时,熔体流动速率提高了38.4倍;LSSF增强的HDPE/UHMWPE复合材料的摩擦系数和磨损量都低于HDPE/UHMWPE复合材料,当添加的纤维含量为15%时,摩擦系数和磨损量分别降低了60%和72.9%。分析复合材料磨痕的SEM照片得出,磨粒磨损和黏着磨损是主要的磨损机理。

Si_p/ZA40复合材料磨损性能研究

采用磨损试验研究了干磨擦和油润滑摩擦条件下,硅含量对含硅高铝锌基复合材料磨损性能的影响。应用扫描电子显微镜分析了复合材料磨面的形貌特征。结果表明,含硅高铝锌基复合材料的耐磨损性能优于基体合金;在油润滑条件下,硅含量越高,复合材料的耐磨性能越好;在干摩擦条件下,硅含量为4.5%复合材料的耐磨性能优于其它试验材料。含硅材料的磨损机理是微切削磨损、表面脱落和磨粒磨损的综合作用。

实时温度和磨粒条件下氟橡胶密封圈摩擦磨损特性研究

橡胶密封件的磨损失效严重影响了其使用寿命,而井下钻进时地层温度导致的密封件力学性能衰减和岩屑侵入导致的材料磨损失效都是加剧橡胶密封件失效的重要因素。为探讨氟橡胶(FKM)密封件在实时温度环境和磨粒条件共同作用下的磨损失效机制,通过模拟井下实际工况,研究实时温度对氟橡胶密封件力学性能的影响,开展实时温度下氟橡胶密封件与SS304钢配副的磨粒磨损实验,探究橡胶力学性能变化导致温度和磨粒条件下FKM/SS304配副接触形式转变的原因,并分析氟橡胶密封件磨损机制变化以及对摩擦因数、磨损量以及配副表面磨损形貌等的影响。结果表明:氟橡胶硬度、弹性模量等力学性能指标在实时温度升高至60℃时发生明显衰退,力学性能的衰退使密封副之间的接触形式由三体接触转变为二体接触;橡胶表面磨损形貌由60℃之前的三体磨损导致的凹坑转变为二体磨损时的表面材料剥离,金属表面磨损形貌也由犁沟为主转变为划痕损伤;橡胶磨屑形貌也因磨损机制变化逐渐转变成条状磨屑。研究结果为井下钻进机具密封件材料的选择及性能优化提供依据。

热等静压Al_2O_3/SiC和SiC_w/SiC陶瓷磨粒磨损行为的比较研究

通过 SEM观察和 EDXA分析对 Al2 O3/ Si C和 Si Cw/ Si C陶瓷的耐磨粒磨损性进行了比较研究。在低应力下 ,Al2 O3/ Si C陶瓷的耐磨性优于 Si Cw / Si C陶瓷 ,而在较高应力下则相反。陶瓷的塑性、韧性、硬度、微观结构和外加应力都对其磨粒磨损行为起作用。各样品的磨损均由单颗粒脱落和块状脱落构成。

钴铬粘结相对碳化钨涂层磨粒磨损性能的影响

采用超音速火焰喷涂(High-velocity Oxygen-fuel Spraying,简称HVOF)工艺在30CrMnSiA基材表面制备了Co和CoCr粘结相质量分数分别为12%、14.5%和17%的三种WC复合涂层,研究了涂层显微组织结构、物相组成以及粘结相Co、Cr含量对WC涂层显微硬度和耐磨粒磨损性能的影响,采用扫描电子显微镜观察涂层磨损前后的表面形貌,探讨了WC复合涂层的磨粒磨损机理。结果表明:超音速火焰喷涂WC复合涂层组织致密,涂层与基体结合良好,存在少量夹杂,涂层孔隙率均小于1%,涂层存在少量氧化物;粉末材料在喷涂过程中存在氧化和分解脱碳,生成了少量W_(2)C和Co_(3)W_(3)C两种脆性相,含Cr的涂层中发现了少量Cr_(3)C_(2);在一定范围内,随着粘结相Co、Cr含量的增加,超音速火焰喷涂WC复合涂层显微硬度降低,耐磨粒磨损性能下降,三种涂层中粘结相含量为12%的WC涂层的耐磨粒磨损性能最佳,粘结相含量为17%的WC涂层的耐磨粒磨损性能最差;超音速火焰喷涂Co和CoCr粘结相质量分数分别为12%、14.5%和17%的WC复合涂层在白刚玉磨粒环境中磨粒磨损机制均为微切削和大颗粒WC硬质相疲劳剥落。

Q235钢表面B-C-S共渗及其氩弧重熔层的磨损性能

为了提高Q235钢的耐磨性，利用粉末包埋法在其表面制备了B-C-S共渗层，采用氩弧重熔工艺进行普通氩弧重熔及活性氩弧重熔，以现代表面分析技术测试了B-C-S共渗层及重熔后的物相组成、显微组织、显微硬度及其耐磨性能。结果表明：B-C-S共渗层获得了性能较好的Fe2B，Fe3c和具有减磨特性的FeS等新相；普通氩弧重熔后有Fe3（c，B，S）相生成，活性氩弧重熔后产生了Fe3（c，B），Fe2386，Fe3Si，Fe3Al等新相；B-C-S共渗层的显微硬度高达1022HV，2种重熔层的分别是834Hv和739HV；共渗层、普通氩弧重熔和活性氩孤重熔后的耐磨粒磨损性能较基体分别提高了1．67．2．69，6．27倍。

SiC基树脂磨刷材料的制备及性能

文章以SiC为磨料,环氧改性酚醛树脂作为粘结剂,再配取偶联剂、蜂蜡等适当的填料,通过热压成型工艺制备3组不同配方的试样.试验结果表明：磨块力学性能随SiC含量增加而提高,在SiC质量分数为83％时,磨块M2硬度与结合强度达到最佳.当载荷、速度恒定时,磨块摩擦因数随SiC含量的增加呈现出先降低而后稳定的趋势,在文章试验条件下,M2摩擦因数稳定在0.3466 ～0.4038之间,其磨耗比检测值为45.

Microstructure and Abrasive Wear Behavior of Medium Carbon Low Alloy Martensitic Abrasion Resistant Steel

The effect of processing parameters such as hot rolling and heat treatment on microstructure and mechanical properties was investigated for a new 0.27mass% C and Ni, Mo-free low alloy martensitic abrasion resistant steel. The three-body impact abrasive wear behavior was also analyzed. The results showed that two-step controlled rolling besides quenching at 880 ℃ and tempering at 170 ℃ could result in optimal mechanical property., the Brinell hardness, tensile strength, elongation and --40 ℃ impact toughness were 531, 1530 MPa, 11.8% and 58 J, re- spectively. The microstructure was of fine lath martensite with little retained austenite. Three-body impact abrasive wear results showed that wear mechanism was mainly of plastic deformation fatigue when the impact energy was 2 J, and the relative wear resistance was 1.04 times higher than that of the same grade compared steel under the same working condition. The optimal hardness and toughness match was the main reason of higher wear resistance.

Feasibility of new ladle-treated Hadfield steel for mining purposes

A debate has arisen over the possibility of using a new ladle-treated Hadfield steel instead of conventional heat-treated Hadfield steel in mining applications. This debate might be solved by identifying the differences between the mechanical properties and strain-hardening properties of conventional heat-treated Hadfield steel and its counterpart ladle-treated Hadfield steel. Tensile and compression tests demonstrated that the ductility of ladle-treated Hadfield steel is similar to that of conventional heat-treated steel. However, the strain-hardening property of the ladle-treated Hadfield steel is almost two times higher than that of the heat-treated Hadfield steel. The results of this study demonstrate that the improvement of the strain-hardening behavior is attributable to the low stacking-fault energy of the main austenite matrix, which results from the high segregation coefficient of carbon and manganese solutes of the main austenite matrix into the new eutectic phase. Superior wear abrasion resistance is a potential consequence of different strain-hardening properties under low and high loads.

Investigations on Mechanical and Tribological Behaviour of Particulate Filled Glass Fabric Reinforced Epoxy Composites

The aim of the research article is to study the mechanical and two-body abrasive wear behaviour of alumina (Al2O3) filled glass fabric reinforced epoxy (G-E) composites. Alumina filled G-E composites containing 0, 5, 7.5 and 10 wt% were prepared using the hand lay-up technique followed by compression molding. The mechanical properties such as tensile strength, hardness and tensile modulus were investigated in accordance with ASTM standards. Two-body abrasive wear studies were carried out using a pin-on-disc wear tester under multi-pass condition against the water proof silicon carbide abrasive paper. From the experimental investigation, it was found that the presence of?Al2O3 filler improved the tensile strength and tensile modulus of the G-E composite. Inclusion of Al2O3 filler reduced the specific wear rate of G-E composite. The results show that in abrasion mode, as the filler loading increases the wear volume decreases and increased with increasing abrading distance. The excellent wear resistance was obtained for Al2O3 filled G-E composites. Furthermore, 10 wt% filler loading gave a very less wear loss. Finally, the scanning electron microscopic observations on the wear mechanisms Al2O3 filled G-E composites was discussed.

纳米金刚石磨粒团聚对熔石英摩擦磨损性能的影响

为了研究磁流变抛光液中磨粒团聚对光学玻璃元件的磨损性能,利用环境可控的直线往复式摩擦磨损试验机,以不锈钢球为对磨副,以熔石英为基底,系统地研究了磁流变抛光液中纳米金刚石磨粒团聚程度对熔石英摩擦磨损性能的影响,并利用光学显微镜、白光干涉仪等设备分析熔石英的磨损机制,最后将摩擦学实验结果与实际磁流变抛光结果进行对比。实验结果表明:纳米金刚石磨粒团聚程度越大,熔石英表面的材料去除率越大,磨损区域亚表面损伤情况越严重。当载荷为0.5 N时,熔石英在团聚磨粒作用下的磨损主要以黏着磨损为主,伴随着轻微的磨粒磨损,同时熔石英的亚表面无明显损伤;当载荷从0.5 N增加到4 N时,熔石英的磨损形式以磨粒磨损为主,熔石英的表面和亚表面出现大量损伤。采用相同磨粒团聚程度的抛光液进行熔石英磨损与磁流变抛光实验发现,熔石英在磁流变抛光过程中的材料去除率与磨损实验的材料去除率变化趋势保持一致,表明借助摩擦磨损实验在一定程度上可以预测实际磁流变抛光中的材料去除率。

碱处理核桃壳粉/PVC复合材料制备与性能

为研究碱处理对核桃壳粉/PVC复合材料(WPC)性能的影响,以浓度为0~7%的NaOH处理的核桃壳粉为生物填料,以聚氯乙烯(PVC)为基体,采用单螺杆熔融挤出工艺制备WPC,并对复合材料的化学成分、热稳定性、微观形貌及物理、力学和抗磨料磨损性能进行表征和分析。结果表明,与未处理时相比,碱处理后,WPC的硬度、密度、吸水率、拉伸强度、冲击强度均显著提高,密度和吸水率随着碱处理浓度的增大而升高,当采用3%的NaOH碱处理后,WPC的硬度、拉伸强度和弯曲强度均达到最大,与处理前相比,分别提高了3%、7%和1%;当采用5%的NaOH碱处理后,WPC的冲击强度最高,与处理前相比,提高了15%。碱处理还提升了WPC热稳定性和耐磨性,并且,经过3%碱处理后的WPC的热稳定性最佳,其热解残余质量与处理前相比,提高了73%;经过5%碱处理后的WPC的耐磨性最佳,其磨损失重及比磨损率与处理前相比,分别降低了53%、51%。