Investigation of erosive wear behavior and physical properties of SGF and/or calcite reinforced ABS/PA6 composites

The aim of this study was to investigate the erosive wear behavior of glass fiber, CaCO₃ particle and glass fiber/CaCO₃ hybrid reinforced ABS/PA6 blend based composites. The samples were prepared by using melt mixing and injection molding techniques. The mechanical, thermal, morphological properties and erosive wear behavior were investigated in terms of reinforcing agent type and composition. It was observed that the tensile strength and modulus values of hybrid composites gave a value between tensile strength and modulus values of only fiber reinforced composites and only particle reinforced composites. From DSC analysis it was revealed that T_g and T_m of composites were not significantly affected by reinforcement; however, degree of crystallinity was found to be sensitive to reinforcement type and composition. The impingement angle was found to have a significant effect on the erosive wear behavior. The results indicated that composite materials exhibited maximum erosion rate at impact angle of 30° conforming their ductile erosion behavior. In order to investigate wear mechanisms, eroded surface analysis was done by scanning electron microscopy. Surface analysis showed that repeated impact of hard silica sand particles caused a local removal of the matrix from the fiber surface and led to form craters on the surface of the composite material.     

Influence of ion implantation and overlay coatings on various physico-mechanical and wear properties of stainless steel,titanium and aluminium

This work represents the data on the wear behaviour of 304 stainless steel, commercial grade titanium and commercial grade aluminium without and with different surface treatments, namely ion implantation of boron and nitrogen and overlay coatings of titanium carbide and nitride.The surface treatments were characterized by phase identification, hardness, bend strength, as well as adhesion of overlay coatings. Wear properties were evaluated in adhesive, erosive and abrasive modes of wear.The experimental results showed that surface treatments produced measurable changes in hardness and strength. The results of adhesive wear tests indicated that the wear resistance of all the substrate materials can be considerably improved by overlay coating with superhard materials in dry as well as lubricated test conditions. Ion implantation resulted in improvement of wear properties for only a limited regime of adhesive wear under lubricated conditions and for the abrasive mode of wear. Overlay coatings produced a marked improvement in abrasive wear tests under lubricated conditions on all substrate materials.     

Effect of stress on abrasive and erosive wear of steels and sprayed coatings

The effect of stress on abrasive and erosive wear was studied for the hypoeutectoid steel, two hypereutectoid tool steels and flame sprayed coatings. In the experiment, the specially designed tester as well as SEM and contact profilometer were applied. Abrasion and erosion remove asperities protruding from the surface of coatings. The imposed stress increased erosive wear of coatings. Application of compressive stress to steels reduces roughness of the wear scar. Compressive stress caused distinct damage localization in abraded and eroded coatings, mean spacing of surface irregularities Rsm observed in erosion test was about 50% larger than in unstressed coatings. Results of fractal analysis confirm stress-induced change in surface topography.     

Scanning electron microscopy study of the effect of the brushing time on the human tooth dentin after exposure to acidic softdrinks

Scanning electron microscopy (SEM) was used to examine the abrasive and erosive potential of the brushing time on the dentin surface eroded by acidic soft drinks to suggest an optimized toothbrushing start time after the consumption of cola (pH 2.52) in children. Thirty-six non-carious primary central incisors were assigned to 12 experimental groups (n = 3) based on the erosive and abrasive treatment protocols. Cola exposure was used as the erosive treatment. Three brushing durations (5, 15, and 30 sec) and four brushing start times (immediately, 30 min, 60 min, and 120 min) after an erosive pre-treatment were used for the abrasive treatment. Toothbrushing after exposure to acidic soft drinks led to an increase in the open-tubule fraction and microstructural changes. Toothbrushing immediately after the erosive pre-treatment showed the largest abrasive and erosive potential on the dentin whereas that 60 and 120 min after the pre-treatment showed the least abrasive and erosive potential on the dentin. Toothbrushing for both 60 and 120 min after the pre-treatment showed similar erosive and abrasive potentials on the dentin. The brushing duration showed no effect on the erosive and abrasive potential on the dentin. Therefore, to achieve the desired tooth surface cleaning and less surface lesion on the dentin surface, toothbrushing should be performed at least 1 hour after cola consumption. Three-minute brushing after cola consumption is sufficient to prevent dental lesions, and prolonged brushing can irritate the gingival tissues.     

Erosive Wear and Wear Mechanism of in situ TiCp/Fe Composites

1.IntroductionMetal-based composite is a kind of environmental ma-terial that can be reused.It combines the beneficialproperties of the metal matrix,such as ductility,goodthermal and electrical conductivity and high toughness,with those of the reforcement phase[1~3].The latter isusually a ceramic,serving to increase the elastic modu-lus,shear strength and hot strength,fatigue and wearresistance.Its development has been widely studied[4~8].Wear of metal materials causes a tremendous loss of ec…     

陶瓷颗粒增强镍合金复合涂层冲蚀磨损的试验研究

以WC,ZrO₂,Cr₂O₃和Al₂O₃陶瓷颗粒为增强相,镍合金粉末为基体,运用等离子喷涂技术制备四种陶瓷/镍合金复合涂层。采用冲蚀磨损试验机和正交试验方法,进行陶瓷颗粒相浓度、磨粒粒度、冲蚀角和速度对陶瓷颗粒/镍合金复合涂层抗冲蚀磨损性能影响的试验研究。采用表面形状测量仪对陶瓷颗粒/镍合金复合涂层磨损表面形貌进行测量和分析。试验结果得到WC,ZrO₂,Cr₂O₃和Al₂O₃四种陶瓷颗粒/镍合金复合涂层冲蚀磨损率的经验关联式。     

金属基表面Al2O3-SiO2涂层耐冲蚀性能的研究

结合炼钢转炉用风机因炉气而导致叶片磨蚀较快的实际情况，从改善叶片材料的角度出发，采用溶胶-凝胶法制备Al2O3-SiO2涂层用在金属基体上进行试验。结果表明在含3％（质量分数）Si02磨粒的水介质中，单一三层的SiO2涂层、SiO2-Al2O3-SiO2涂层及混合溶胶制备的复合涂层的耐冲蚀性相近，均比单一三层的Al2O3涂层及A12O3-Sio2-Al2O3涂层好。混合溶胶制备的复合涂层在3％（质量分数）SiO2磨粒的酸性介质中表现出了良好的耐冲蚀性。     

Characterization of mechanical properties and three‐body abrasive wear of functionally graded aluminum LM25/titanium carbide metal matrix composite

Several engineering components require location specific performance under operating conditions. A compositional/microstructural gradient can provide the performance required at specific locations and these materials were named as functionally graded materials. Functionally graded aluminium metal matrix composites were generally established for the tribo‐components where high wear resistance was a necessity. Reports on three body abrasive wear behaviour of functionally graded materials was limited to date. In the present work, a new functionally graded system comprising aluminium/titanium carbide (10 wt%) was produced through stir casting route followed by centrifugal casting technique and its three body abrasive wear behaviour was investigated. Hollow cylindrical part with the dimensions of length 150 mm, outer diameter 150 mm and thickness 16 mm was obtained. Microstructural study was performed on outer (1 mm) and inner surface (13 mm) to analyze the compositional gradient across the thickness of the functionally graded composite. Hardness was measured on different surfaces along the radial distance from outer periphery and tensile test was conducted on the outer and inner zone. Abrasive wear test was conducted on different surfaces of the functionally graded composite under various loads and speeds at constant time. The microstructural results revealed that particle segregation was more at the outer surface and less at the inner surface. Wear test results showed that increase in wear rate was obtained with increase of load and decrease in wear rate was obtained with increase of speed. The outer surfaces of the functionally graded composite had greater mechanical properties and better wear resistance compared to other surfaces. Scanning electron microscopy analysis was done on the abraded surfaces and observed wear mechanisms were interpreted.     

Study of Abrasive Wear Volume Map for PTFE and PTFE Composites

The potential of this work is based on consideration of wear volume map for the evaluation of abrasive wear performance of polytetrafluoroethylene (PTFE) and PTFE composites. The fillers used in the composite are 25% bronze, 35% graphite and 17% glass fibre glass (GFR). The influence of filler materials, abrasion surface roughness and applied load values on abrasive wear performance of PTFE and PTFE composites were studied and evaluated. Experimental abrasive wear tests were carried out at atmospheric condition on pin-on-disc wear tribometer. Tests were performed under 4, 6, 8 and 10 N load values, travelling speed of 1 m/sec and abrasion surface roughness values of 5, 20 and 45 μm. Wear volume maps were obtained and the results showed that the lowest wear volume rate for PTFE is reached using GFR filler. Furthermore, the results also showed that the higher is the applied load and the roughness of the abrasion surface, the higher is the wear rate. Finally it is also concluded that abrasive wear process mechanism include ploughing and cutting mechanisms.     

Cu对粉末冶金Fe3Al基复合材料性能的影响

研究了Cu含量对粉末冶金Fe3Al基复合材料的烧结性能和力学性能的影响,分析了施加载荷和改变转速对加入不同量铜粉末冶金Fe3Al基复合材料的摩擦磨损性能的影响,并借助电子显微镜和能谱分析了不同铜含量Fe3Al基复合材料的磨损机理.结果表明:加入12%的Gu可使Fe3Al基复合材料具有良好的烧结性能和力学性能;载荷和转速对复合材料的磨损形式受铜的加入量的影响;铜的加入影响复合材料的磨损形式和磨损机理,当含铜量较少时,复合材料以磨粒磨损为主,随加入铜的量的增多,其磨损形式变为磨粒磨损和轻微的粘着磨损形式,加入大量铜时,则以粘着磨损为主.     

A study on the abrasive and erosive wear behavior of arc-deposited Cr-N-O coatings on tool steel

In this study, the cathodic arc evaporation technique, by using the chromium target and controlling the flow rate of nitrogen/oxygen reactive gases, was utilized to deposit three different Cr-N-O coatings (CrN, CrN/Cr(N,O), CrN/Cr₂O₃) on AISI M2 tool steel. Two types of wear tests were applied to evaluate the abrasive and erosive wear behavior of the coated and uncoated specimens. One was the ball-on-disk abrasion test to measure the friction coefficient of these specimens. The other was the erosion test using Al₂O₃ particles (~ 177 µm in size and Mohr 7 scale) of about 5 g, and then the surface morphologies of the eroded specimens were observed. To further understand the coating effects on the two wear behaviors of M2 steel, coating structure, morphology, and adhesion were analyzed using XRD, SEM, and TEM, respectively. The results showed that surface roughness and adhesion of the double-layered coatings (CrN/Cr(N,O) and CrN/Cr₂O₃) were inferior to those of monolithic CrN, but their hardness and elastic modulus were superior to those of CrN. In the abrasive behavior, Cr-N-O coatings reduced the friction coefficient of M2 substrate. In particular, the CrN/Cr₂O₃ has the highest hardness/elastic (H/E) modulus ration, therefore the lowest friction coefficient, among all the coated-specimens tested. In the erosive behavior, the coated specimens exhibited better erosion resistance as compared to the uncoated ones, at the impingement angles of either 30^o or 90^o. Moreover, the erosion resistance of CrN/Cr(N,O) coatings was superior to that of CrN/Cr₂O₃ coatings due to its better adhesion.     

T8钢—聚有机硅氧烷仿生减粘降阻复合涂层的特性

研究了Ｔ８钢－聚有机硅氧烷仿生减粘降阻复合涂层的表面润湿性，磨料磨损性及土壤的减粘降组性能，与金属材料相比，仿生复合涂层的表面憎水性显著提高，水在其表面上的接触角达９２°；与４５钢相比，其磨料磨损的体积相对耐磨系数为６３％，降阻率达１５．２２％－－２２．２７％。     

不同磨粒含量下过共晶成分铝锰基复合材料的冲蚀磨损性能

采用MSH型磨损试验机将过共晶成分Al—Mn合金及A1203颗粒增强过共晶成分铝锰基复合材料在3．5m／s速度下进行不同磨粒粒度和不同磨粒含量的冲蚀磨损试验，分析了两种材料的组织结构，并对材料的失重率、抗冲蚀磨损性能、微观失效表面形貌进行了研究和讨论。结果表明：两种材料的冲蚀磨损失重率随着磨粒含量的增加明显增大；在3％磨粒加入量下二者的失重率随着磨粒粒度的增大均呈现出先增大后减小的趋势，且随着磨粒含量的增加两种材料在较大粒径下出现增重的现象消失。此外，在锰含量相近的条件下A120s颗粒增强过共晶成分铝锰基复合材料的抗冲蚀磨损性能优于过共晶成分铝锰合金。     

Effects of Lubricant Condition and Tool Wear in Hard Turning of Novel-Abrasion-Resistance (N-AR) Cast Iron

Advanced materials, such as high abrasion resistant cast iron, have great applications for abrasive and erosive environments. Since the amount and the hardness of the microstructural carbides constituents in this material is extremely high, the abrasion-resistance cast iron is generally difficult to be machined with traditional cemented carbide tool. The hard and abrasive particles in this material can remarkably shorten the cutting tool life through abrasion of tool face and deterioration of cutting edge. In this article, Cubic Boron Nitride (CBN) cutting tool has been used to machine a novel-abrasion-resistance (N-AR) cast iron. The performances of CBN tool under different lubrication conditions were evaluated in view of tool wear, cutting force, and surface roughness (Rz). Further more, the wear rate of CBN tool under different machining condition and the mechanism of the CBN tool in machining of this type of work materials has also been investigated.     

新型填料对高摩复合材料摩擦磨损性能影响及机制

采用干法热压成型工艺制备高摩复合材料,研究了基体材料腰果壳油改性酚醛树脂(CPR)与丁晴橡胶(NR)的质量比和新型高性能填料(主要成分为石墨粉Al2O3、MoS2、Fe粉)含量对高摩复合材料摩擦磨损性能的影响规律。在摩擦磨损试验机上测试了高摩复合材料的摩擦磨损性能,利用激光共聚焦显微镜、扫描电镜对摩擦表面形貌、磨屑进行观察和分析,借助EDS测定摩擦表面成分的变化。结果表明,随着CPR与NR质量比的增加,高摩复合材料的耐热性能、结合性能大幅提高,且具有较好的摩擦磨损性能。当高性能填料含量较低时,磨损表面出现大量连续的真实接触面,磨损机制为磨粒磨损和黏着磨损;当高性能填料含量较高时,真实接触面积减少,磨损表面剥落严重,并出现较多的裂纹,其主要磨损形式转变为磨粒磨损和疲劳磨损。随着高性能填料含量的增加,摩擦表面的元素从均匀分布逐渐转变为局部富集,磨粒的尺寸逐渐变大。     

Influence of fibre orientation on three-body abrasive wear behaviour of unidirectional carbon fibre-reinforced polyetherimide composite

Three-body abrasive wear behaviour of neat polyetherimide (PEI) and unidirectional carbon fibre-reinforced PEI (CF/PEI) has been studied using a rubber wheel abrasion test rig. The abrasive wear studies were carried out at different loads (5–20 N) at a constant sliding velocity (v = 2.4 m/s) of rubber wheel. The influence of fibre orientation, i.e. parallel (P-fibre orientation) and anti-parallel (AP-fibre orientation) on wear rate of CF/PEI composite has also been studied. The results showed that the fibre orientation has a significant influence on the three-body abrasive wear behaviour of CF/PEI. The abrasive wear rate was higher when fibres are oriented at anti-parallel than that of parallel orientation of fibres. The worn surfaces have been observed using scanning electron microscope to understand the possible wear mechanisms involved during material removal processes.     

Mechanical and three-body abrasive wear behaviour of three-dimensional glass fabric reinforced vinyl ester composite

The mechanical and three-body abrasive wear behaviour of two- and three-dimensional E-glass woven fabric reinforced vinyl ester composites were studied in this article. The mechanical properties were evaluated using universal testing machine as per ASTM D-638. Three-body abrasive wear tests were conducted using rubber wheel abrasion tester (RWAT) under different abrading distances at two loads, wherein the wear volume loss were found to increase and that of specific wear rate decrease. The results indicate that the three-dimensional glass woven fabrics in vinyl ester (G_3D–V) have significant influence on wear under varied abrading distance/loads. Further, it was found that G_3D–V composite exhibited lower wear rate compared to two-dimensional glass woven fabric reinforced vinyl ester (G_2D–V) composite. The worn surface features, as examined through scanning electron microscope (SEM), show ruptured glass fiber in G_2D–V composite compared to G_3D–V composites.     

电刷镀Ni-CNTs/PTFE纳米复合镀层的摩擦磨损与耐腐蚀性能

再制造工程中很多表面镀层要求具有优异的摩擦磨损与耐腐蚀性能,利用纳米电刷镀技术在45钢基材上制备NiCNTs、Ni-CNTs/PTFE、Ni-WC/PTFE-CNTs复合镀层。采用XRD和SEM观察电刷镀复合镀层表面相结构和微观形貌,采用球盘式摩擦磨损试验机测试其在干摩擦条件下的摩擦磨损性能,采用动电位极化曲线研究其在3.5%NaCl溶液中的电化学腐蚀行为。结果表明:Ni-WC/PTFE-CNTs复合镀层耐磨性能最优,其次为Ni-CNTs/PTFE、Ni-CNTs复合镀层,均强于纯镍镀层;当CNTs质量浓度分别为1.5g/L和1.0g/L时,Ni-CNTs复合镀层分别表现出最优的摩擦磨损性能和最佳的耐腐蚀性能,Ni-WC/PTFE-CNTs、Ni-CNTs/PTFE复合镀层次之。纯镍镀层和Ni-CNTs复合镀层的磨损机制是粘着磨损,Ni-CNTs/PTFE复合镀层的磨损机制主要是粘着磨损,其次为磨粒磨损,Ni-WC/PTFE-CNTs复合镀层的磨损机制主要是磨粒磨损和接触疲劳磨损。     

以自蔓延高温合成SiC颗粒为增强体的光学/仪表级铝基复合材料

尝试采用自蔓延高温合成（SHS）、具有近球特征且表面粗糙的新型SiC颗粒,以替代传统的角状磨料级SiC颗粒,作为光学/仪表级的高体分SiCp/Al复合材料的增强体。研究结果表明：与传统角状SiC颗粒相比,SHS-SiC颗粒的无棱角,近球形几何特征,使其附近铝基体中的应力集中程度显著降低,进而使材料的强度包括表征尺寸稳定性的微屈服强度明显提高：SHS-SiC颗粒所特有的粗糙表面形貌,使SiC-Al之间的界面结合通过机械镶嵌机制得到了进一步的增强,跨越界面的载荷传递效率进一步提高,并表现为复合材料的弹性模量有所提高。     

PARTICLE-SIZE DISTRIBUTION INFLUENCE IN HIGH-SPEED EROSION OF ALUMINIUM

The paper discusses the influence of the abrasive particle-size distribution on typical high speed abrasive-waterjet erosion parameters. The size distributions of the used abrasive particles are modelled by a Rosin-Rammler-Sperling (RRSB) grain-size distribution containing the distribution parameters D and n. Both parameters are independently varied to characterise different particle-size distributions. Aluminium specimens are eroded by abrasive-waterjets at velocities of 320 m/s, and the erosion depth, depth distribution, and the surface roughness are measured. The depth distribution and the surface roughness are very sensitive to the particle-size distribution parameters, whereas the average erosion depth is not influenced significantly. These results offer the possibility to select an “optimum” grain-size distribution for maximum surface quality at fixed kinematics conditions.