Corrosive-wear behavior of LSP/MAO treated magnesium alloys in physiological environment with three pH values

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Yongshui Shen ◽  
Tongjin Sun ◽  
Tao Zhu ◽  
Ying Xiong

Abstract A laser shock peening (LSP) layer, a micro-arc oxidation (MAO) coating, and an LSP/MAO composite coating were fabricated on the surface of AZ80 magnesium alloy by laser shock and micro-arc oxidation process. The ball-disc grinding method was used to perform wear test on the three treated specimens in simulated body fluids (SBF) with pH values of 4, 7.4 and 9. The morphology and element content of worn surface were investigated by scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The results indicated that the wear rates of the three treated specimens in three pH environment in numerical order were pH 4 > pH 7.4 > pH 9, respectively. The wear rates of the three treated specimens in the same pH environment were arranged in the order of MAO > LSP > LSP/MAO, respectively. The main wear mechanisms of the LSP specimen in pH 4 environment were fatigue wear and corrosion wear, while it were corrosion wear and adhesive wear in pH 7.4 and pH 9 environments. Abrasive wear, fatigue wear and corrosion wear were the main wear mechanisms of the MAO specimen in pH 4 environment, while abrasive wear, adhesive wear and corrosion wear were the main wear mechanisms of that in pH 7.4 and pH 9 environments. The corrosion wear resistance of the LSP/MAO specimen in SBF solution with three pH values was improved due to the synergism of LSP fine crystal layer and MAO coating.

Coatings ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 109 ◽  
Author(s):  
Haojun Wang ◽  
Tao Chen ◽  
Weilong Cong ◽  
Defu Liu

Ti-based ceramic coatings on Ti6Al4V substrates were successfully prepared through a laser cladding process using pre-placed starting materials of TiCN + SiO2 mixed powder without or with adding a 3 wt % CeO2 nanoparticles additive, aiming at improving the wear resistance of the Ti6Al4V alloy for biological applications. The effects of the CeO2 nanoparticles additive on the microstructure, microhardness, and wear performance of the coatings were analyzed in detail. The observations showed that the main compositions of the cladding coating were TiCN and TiN phase. Compared to the coatings without CeO2, the coatings modified with CeO2 nanoparticles led to more excellent mechanical properties. The average microhardness of the coatings modified with CeO2 nanoparticles was approximately 1230 HV0.2, and the wear volume loss of the coatings modified with CeO2 nanoparticles was approximately 14% less than that of the coatings without CeO2 under a simulated body fluid (SBF) lubrication environment. The major reasons included that the microstructure of the coatings modified with CeO2 nanoparticles was refined and compact granular crystalline. The wear mechanisms of the coatings were investigated from the worn surface of the coatings, wear debris, and the worn surface of the counter-body balls. The wear mechanisms of the coatings without CeO2 included abrasive wear, adhesive wear, and fatigue wear, while the wear mechanisms of the coatings modified with CeO2 nanoparticles included only abrasive wear and adhesive wear, because the fine microstructure of the coatings had an excellent resistance to fatigue wear.


Author(s):  
Shao Lifan ◽  
Ge Yuan ◽  
Kong Dejun

In order to improve the friction and wear properties of Cu10Al–MoS2 coating, the addition of CeO2 is one of the present research hot spots. In this work, Cu10Al–MoS2 coatings with different CeO2 mass fractions were successfully fabricated on Q235 steel using a laser cladding. The microstructure and phase compositions of obtained coatings were analyzed using an ultra-depth of field microscope and X-ray diffraction, respectively. The friction-wear test was carried out under oil lubrication using a ball-on-disk wear tester, and the effects of CeO2 mass fraction on the microstructure, hardness, and friction-wear properties were studied, and the wear mechanism was also discussed. The results show that the laser cladded Cu10Al–MoS2 coatings with the different CeO2 mass fractions were mainly composed of Cu9Al4, Cu, AlFe3, Ni, MoS2, and CeO2 phases. The Vickers-hardness (HV) of Cu10Al–8MoS2–3CeO2, Cu10Al–8MoS2–6CeO2, and Cu10Al–8MoS2–9CeO2 coatings was 418, 445, and 457 HV0.3, respectively, which indicates an increase in hardness with the increase of CeO2 mass fraction. The average coefficients of friction (COF) and wear rates decrease with the increase of CeO2 mass fraction, presenting the outstanding friction reduction and wear resistance performances. The wear mechanism of Cu10Al–MoS2 coatings is changed from abrasive wear with slight fatigue wear to abrasive wear with the increase of CeO2 mass fraction.


2020 ◽  
Vol 993 ◽  
pp. 836-843
Author(s):  
Ke Guo ◽  
Zhi Qiang Zhang ◽  
Zhong Zheng Pei ◽  
Jie Xu ◽  
Yi Fan Feng

Here we developed a hot-pressed molded resin-based brake pad material reinforced by a nano sodium titanate whisker in comparison with nano potassium titanate whisker. The effect of the whiskers on the tribology behavior was investigated. Though nano sodium titanate whisker reinforced brake material showed higher porosity (+12.29% averagely) and lower hardness (-25.8% averagely) caused by the impurities, it exhibited improved ability in stabilizing the friction coefficient and enhancing 25.5%, 31.1%, 25.9% higher wear resistance, when the volume contents of whisker are 7.5%, 15% and 22.5%, respectively, compared to the nano potassium titanate whisker reinforced brake material. The wear mechanisms of the nano sodium titanate whisker reinforced brake materials were determined as embedded debris, delaminated crater, moderate layers transfer, uniform furrows, primary plateaus and secondary plateaus in similar size, indicating a main wear form of abrasive wear instead of adhesive wear.


2011 ◽  
Vol 188 ◽  
pp. 32-37 ◽  
Author(s):  
An Hai Li ◽  
Jun Zhao ◽  
Z.Q. Pei ◽  
S.G. Guo

The failure progression of coated carbide tools in end milling of Inconel 718 superalloy was investigated. Tool wear was measured and failure mechanisms were discussed in the experimental process periodically. The experimental results indicated that the tool failure mechanisms were synergistic interaction among abrasive wear, adhesive wear, and fatigue wear. However, abrasive wear and adhesive wear were the main failure mechanisms at the beginning, fatigue wear prevailed the upper hand around the time when edge chipping appeared, and after edge chipping abrasive wear and adhesive wear dominated until the failure time. In addition, the macroscopic failure of the cutting tools is closely correlated to the nucleation and propagation of the crack under cyclic mechanical and thermal impact forces. Mechanical fatigue wear was the key form of fatigue wear at lower cutting speed, while at higher cutting speed thermal fatigue wear was the dominant fatigue wear.


2019 ◽  
Vol 799 ◽  
pp. 83-88
Author(s):  
Ewald Badisch ◽  
Markus Varga ◽  
Stefan J. Eder

Abrasive wear limits the lifetime of key components and wear parts used in various applications. Damage is caused by indentation of harder particles into the wearing materials and subsequent relative motion resulting in ploughing, cutting, and fracture phenomena. The wear mechanisms depend mainly on the applied materials, loading conditions, and abrasives present in the tribosystem, hence material choice is often a difficult task and requires careful evaluation. For this, a variety of laboratory abrasion tests are available of which the scratch test is discussed in this work as the most fundamental abrasive interaction. For further insight into the acting wear mechanisms and microstructural effects, large-scale molecular dynamics simulations were carried out as well as meso-/macroscopic scratch simulations with the mesh-free Material Point Method. The prediction of abrasive wear is of high relevance for industrial applications. Up to now, no general one-to-one match between field application and lab system is known. Here, a simulation-based transfer of experimentally determined wear rates via a lab-2-field approach enables the prediction of wear rates in real applications.


2011 ◽  
Vol 311-313 ◽  
pp. 92-95 ◽  
Author(s):  
Kui Chen ◽  
Tian Yun Zhang ◽  
Wei Wei

Polypropylene/organo-montmorillonite (PP/OMMT) composites were investigated by XRD. Friction and wear behaviors of this composites sliding against GCr15 stainless steel were examined on M-2000 text rig in a ring-on-block configuration. Worn surfaces of PP and its composites were analyzed by SEM. The result shows that PP macromolecule chains have intercalated into OMMT layers and form intercalated nanocomposites. With the increase of mass fraction of OMMT, both wear rate and friction coefficient of composites first decrease then rise. With the increase of load, from 150 N, 200 N to 250 N, wear rate of composites increases, while friction coefficient reduces. The wear mechanisms of composites are connected with the content of OMMT. Composites were dominated by adhesive wear, abrasive wear and adhesive wear accompanied by abrasive wear respectively with the increase of OMMT content.


2011 ◽  
Vol 415-417 ◽  
pp. 2191-2195
Author(s):  
Ye Fa Tan ◽  
Bin Cai ◽  
Long He ◽  
Sheng Qiang Hao ◽  
Hua Tan ◽  
...  

Weldox960 steel is widely used in mechanical structure of military equipments as anti-wear parts. The tribological behavior and mechanisms of weldox960 steel were investigated under dry sliding friction conditions. The results show that friction coefficient of the steel increases from 0.268 to 0.365 with the increase of load. When the loads are smaller than 8N, the wear rates of the steel are in the range of 0.57~0.67×10-3 mm3/m, and the wear mechanism is multi-plastic deformation wear. If the loads are bigger than 10N, the wear rates increase to the range of 1.29~1.43×10-3 mm3/m, and the wear mechanisms change into delamination of the work-hardening layer and abrasive wear. The friction coefficients keep in a steady state of about 0.31 when the sliding speeds change from 0.05m/s to 0.2m/s. At the low speeds of 0.05m/s and 0.1 m/s, the wear rates are in the range of 1~1.3×10-3 mm3/m and the wear mechanisms are multi-deformation wear and abrasive wear. When the sliding speed increases to a critical value of 0.15m/s, the wear rates increase to 6.2×10-3 mm3/m and the wear mechanisms change into fatigue delamination of the work-hardening layer and multi-plastic deformation wear as well as oxidation wear.


2010 ◽  
Vol 113-116 ◽  
pp. 1930-1934
Author(s):  
Zhen Duo Han ◽  
Chao Qu ◽  
Yu Xing Peng ◽  
Guo An Chen ◽  
Yi Lei Li

A wear tester was developed. MC PA (nylon) filled with MoS2 and PU (polyurethane) were used as the material of the rubber wheel of roller guide shoes. Their wear performances was investigated with the tester. The results show that the wear rate of MC PA increases firstly and then decreases with increasing load, and reverses with increasing velocity. The wear rate of PU decreases firstly and then increases with increasing velocity. In addition, the main wear mechanisms of PU are plough wear and abrasive wear at the low load (200N). At the loads of 200N~500N, the main wear form of MC PA is the adhesive wear. Adhesive wear is the main mechanism of MC PA at the low velocity (3m/s). Due to inner heat accumulation by friction, squama-peering occurs on MC PA surface at the high velocity (8m/s). The dominant wear mechanisms of PU are abrasive wear and fatigue pitting. And the main reason of PU’s failure is the interior heat accumulation caused by friction.


2019 ◽  
Vol 72 (3) ◽  
pp. 359-368
Author(s):  
Hulin Li ◽  
Zhongwei Yin ◽  
Yanzhen Wang

Purpose The purpose of this paper is to study the friction and wear properties of journal bearings under different working conditions. Design/methodology/approach Friction coefficient and wear losses of journal bearing under different working conditions have been determined by a bearing test rig. The worn surfaces of bearing were examined by scanning electron microscopy and laser three-dimensional micro-imaging profile measurements, and the tribological behavior and wear mechanisms were investigated. Findings The wear loss and friction coefficient of bearing under starting-stopping working condition is far greater than that of steady-state working conditions. In addition, the maximum wear loss under start-up and stop conditions is about 120 times of that under stable operating conditions. Under stable working conditions, the main wear forms of bearings are abrasive wear, under starting-stopping working conditions the main wear mechanisms of bearings are adhesion wear, abrasive wear and fatigue wear. Originality/value These research results have certain practical value for understanding the tribology behavior of journal bearings under different working conditions.


Metals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 351
Author(s):  
Xiongfeng Hu ◽  
Fuqiang Lai ◽  
Shengguan Qu ◽  
Yalong Zhang ◽  
Haipeng Liu ◽  
...  

Increasing load requirements and harsh operating conditions have worsened the wear of drive shafts in special field vehicles. In this paper, the evolution of the microstructure and fretting wear behaviors of 25CrNi2MoVE torsion shaft steel and their influence on the wear mechanisms were investigated as a function of tempering temperature. The results showed that the coarse grain size, low matrix hardness and non-metallic inclusions in the as-received state lead to a high wear rate and serious adhesive wear. The grain refinement after normalizing and the formed M5C2 carbide and bainite helped to improve the wear resistance and worn surface quality. Low temperature tempering is conducive to further improve the wear resistance of normalized samples, and the wear rate and worn surface roughness are increased gradually after tempering temperature increases. For quenching, although martensite structure can achieve a lower wear rate, the coefficient of friction is much higher; the wear mechanisms are primarily fatigue wear and adhesive wear. Although the adhesive wear degree and worn surface roughness were increased, the optimal anti-wear performances are obtained under tempering at 350 °C with good continuity of the surface oxide film. Excessive tempering temperature will make the softened matrix unable to form a beneficial “third-body wear”.


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