Some views on the construction of bio-tribo-corrosion maps for Titanium alloys in Hank's solution: Particle concentration and applied loads effects

The micro-abrasion-corrosion behavior of a Ti alloy in Hank's solution was investigated using various electrochemical and microscopy techniques. The effects of applied load and particle concentration were assessed for various corrosion, wear and wear-corrosion components of the wastage. Electrochemical potentiodynamic and potentiostatic tests were carried out to assess the effects of tribological variables on the wastage rate. The results were used to generate micro-abrasion-corrosion mechanism, wastage and synergy maps. The potential application of such maps to optimize the materials for total replacement bio-implants is addressed in this paper.     

Effects of dissolved oxygen in saline on corrosive wear of steel

Wear behavior in a corrosive electrolyte where the corrosion reaction is controlled by the diffusion of oxygen cannot be explained only by the removal of corrosion products. The thickness of the oxide layer which varies with test conditions greatly affects the wear rate as well as the corrosion rate. In saline containing O₂ of 1 p.p.m. surface activation was confirmed. Adhesive wear or fatigue wear was found to have a predominant influence on wear behavior. Lubrication by a small amount of oxidation product can be expected to be beneficial. In O₂-saturated saline damage caused by corrosion fatigue is important owing to the intensely corrosive environment. Under O₂-saturated conditions the wear rate is constant under a load P < 3 4 kg, whilst w increases with increasing P above 3 4 kg, which may be considered to be due to the change of contact conditions. Under conditions of O₂-1 p.p.m. wear rate decreases slightly with increase of load because of the more effective lubrication by corrosion products.     

On the synergistic effects of abrasion and corrosion during wear

The interactive effects of abrasion and corrosion were studied as a function of abrasive load, corrosion time and the frequency of abrasive and corrosive treatments. The initial rate of corrosion is independent of abrasive load but the percentage contribution to wear of corrosion decreases with increasing abrasive load. It has also been found that increasing the frequency of exposure to abrasion and corrosion increases the wear loss for a constant total amount of abrasion and corrosion. These effects are discussed in terms of the nature of the work-hardened surface layer and the chemical activity of this layer.     

Wear and corrosion wear of medium carbon steel and 304 stainless steel

Wear and corrosive wear involve mechanical and chemical mechanisms and the combination of these mechanisms often results in significant mutual effects. In this paper, tribological behavior, X-ray peak broadening, and microstructure changes of carbon steel AISI 1045 and stainless steel AISI 304 samples under simultaneous wear and corrosion were investigated and the results were compared with those obtained from dry wear tests. 3.5 wt.% NaCl solution was used as the corrosion agent and a pin-on-disk tribometer was employed to perform wear and corrosive wear tests.X-ray diffraction measurements have shown that by increasing the applied load, the worn surfaces of carbon steel samples reached a constant strain at which fracture and wear occurred. Whereas in 304 stainless steel samples, by increasing the applied load, broadening of X-ray diffraction peaks was decreased.Wear tests of carbon steel and stainless steel samples have shown smaller weight losses and lower friction coefficient in the presence of corrosive environment. Study of worn surfaces suggested that depending on wear environment and applied load, different features of wear mechanisms were involved.     

A Study of Oxidation Phenomena in Corrosive Wear

A mathematical model based on the existing theories of corrosion and wear is proposed for analyzing the controlling phenomena in corrosive wear caused by atmospheric oxygen. The model is applied to experimental wear data, making the assumption that all of the wear proceeded by a corrosion mechanism, i.e., the growth of an oxide layer and its subsequent removal by rubbing. The analytical results show that the rate of metal oxidation is the more important factor in determining the wear rate. The proposed model, assuming oxidation to follow a parabolic rate law, predicts a much higher rate constant and a lower activation energy for oxidation in corrosive wear than in static corrosion at the same “hot spot” temperature. It is postulated that this is due to a mechanical activation phenomena caused by rubbing action. The increase of wear at higher loads can be accounted for by a simple increase in oxidation rate at a higher surface temperature.     

Corrosive Wear Behaviors of Carbon Steels in Oil-Water Fluid

Carbon steel (CS) is the most common material used in oil production. Based on surface wetting state, the corrosive wear behavior of CS in oil-water fluid was investigated. The surface wetting state of the metal in oil-water fluids with different water cut and flow velocity was measured using a specially constructed device. Wear loss, corrosion loss, and corrosive wear loss of the CS samples in different oil-water fluids were measured by a reciprocating corrosive wear tester. The damage morphology of the CS samples was observed using scanning electron microscopy (SEM) and the element distribution on the surface was detected by energy-dispersive X-ray spectroscopy (EDS). The results indicated that the surface water wetting rate of the metal increased with water cut and decreased with flow velocity in the oil-water fluid. Wear, corrosion, and corrosive wear behavior of the CS was related to the surface wetting film and surface reaction film. In this test range, the synergetic action is negative and chlorine embrittlement occurs in the fluid with high water cut and low velocity. The damage mechanism of the CS was abrasive wear with selective corrosion.     

Chemical effects in sliding wear of aluminum

The mechanism of the sliding wear of metals in corrosive media was investigated. In particular, the role of chemical heterogeneities on chemical interactions between the sliding surface and its environment was studied using 2024 aluminum alloy and sodium chloride solutions of varying pH and NaCl concentration. Sliding wear tests with a cylinder-on-cylinder geometry were performed at a sliding speed of 1 m min^?1 and a normal load of 9.8 N (1 kgf). The results show that at pH = 0 and pH = 14, the wear rate is dominated by the dissolution of aluminum into the NaCl solution. In the intermediate pH range, the wear rate is shown to be controlled by the conjoint actions of corrosion and delamination wear. Microscope examination of the worn specimens by means of a scanning electron microscope further confirms that the mode of corrosion is of a localized nature.     

An investigation of the corrosive wear of stainless steels in aqueous slurries

Pumping installations made of stainless steels have been widely used for transporting slurries in chemical process industry. However, knowledge of the attack of stainless steels due to corrosive wear in two-phase liquid-particle flow is still incomplete. This paper studies the behaviors and mechanisms of corrosive wear for two austenitic stainless steels, 24Cr-25Ni-4Mo and 18Cr-12Ni-2Mo, using a rotating disc apparatus made by the authors. The two components, wear by slurry abrasion and corrosion, within the corrosive wear process, are first examined individually. Then the synergistic effect between wear and corrosion is investigated. The research we have done shows that corrosive wear rate of samples is closely related to such factors as the solution, type of abrasive, flow velocity, impingement angle and temperature. In addition, a threshold of flow velocity exists which is called the breakaway velocity V_k, above which the corrosive wear rate increases rapidly. The combined effects of abrasion and corrosion result in a total wear loss larger than the added effects of each process alone. An analytical model is developed which would help to reveal the mechanisms of the corrosive wear processes.     

腐蚀介质条件下NiCrBSi/WC喷熔层的摩擦学性能研究

采用氧-乙炔火焰喷熔工艺,制备了碳化钨颗粒增强镍基合金喷熔层(NiCrBSi/WC),研究了它在腐蚀介质条件下的摩擦磨损行为与机理,并考察了载荷、滑动速度对其摩擦磨损性能的影响规律。研究结果表明:NiCrBSi/WC具有良好的耐腐蚀磨损性能,且当WC含量为20%时,腐蚀磨损率最低;WC含量超过20%后,由于喷熔层存在“腐蚀原电池”效应,其腐蚀磨损率增大。NiCrBSi/WC的腐蚀磨损率随载荷增加而变大,随速度增大而减小。载荷的增加使喷熔层的犁削磨损加剧,导致摩擦系数和磨损率增大;速度的增大造成摩擦界面温度上升,可生成摩擦转移膜,从而降低了喷熔层的磨损率。     

Determination of the wear resistance of traditional ceramic materials by means of micro-abrasion technique

Micro-abrasion techniques enable the surface wear of materials to be studied with greater precision than provided by other methods. In addition to their reliability, micro-abrasion techniques allow the wear phenomenon of the top-most layers to be studied while assuring, in the case of thin coatings, that this is not influenced by the substrate.In the present study, micro-abrasion technique (cratering with a steel ball) was used to determine the wear resistance of traditional ceramic materials, as a complementary test to the methodologies on a macroscopic scale that are customarily used for this type of material. In order to adapt the test to these materials, the individual effect of each test condition on wear resistance was isolated, while keeping the other conditions constant. The following variables were studied: diameter and angular velocity of the ball, abrasive suspension feed rate and grain size, sample–ball contact angle and groove in the supporting drive shaft. The values established were validated by performance of the test on materials of a glassy nature.The micro-abrasion test is shown to be a useful method for studying wear performance of ceramic glazes.     

Micro-abrasion of Y-TZP in tea

The objective of this work is to investigate the micro-abrasion of Y-TZP in tea. This material is a candidate replacement in dental restoration and to date there has been very little work carried out to investigate the wear behaviour in oral cavity conditions. Various additions such as milk and sugar, which affect the solution viscosity and pH, were assessed as part of this work and the results were compared to the performance of the material in aqueous conditions. Wear maps were generated showing the change in wear rate as a function of applied load and exposure time.     

Corrosive wear of carbon and austenitic stainless steels in NaCl solution

The wear rates of an AISI 52100 carbon steel and a type 316 austenitic stainless steel and the corrosion current I from the rubbing steels were measured in NaCl solution to study the interrelationship between the corrosion and wear of the steels. An on-off cyclic loading test was also conducted to examine the effect of static corrosion during an unloading period on the corrosive wear of the steels.

It was found that the wear rates of the carbon steel and the type 316 stainless steel reach a maximum at NaCl concentrations of about 3% and 0.1% respectively. The on-off cyclic test has shown that corrosive wear of the steels is influenced by static corrosion during an unloading period. The increment †I of the corrosion current due to sliding was associated with the corrosive wear rate of the steels.     

Corrosive Wear Performance of Monel K500 Alloy in Artificial Seawater

In corrosive wear, one of the most interesting phenomena is the synergism where both corrosion and wear are significantly increased, leading to much greater material losses than produced by the sum of material losses by either process alone. A systematic investigation was carried out in the present work to assess the electrochemical and corrosive wear behaviors of Monel K500 alloy sliding against alumina in artificial seawater using a pin-on-ring tribometer integrated with a potentiostat for electrochemical control. The open circuit potential clearly shifted to the cathodic direction due to sliding action. The corrosion current density was much higher under sliding than under corrosion only. Moreover, high normal load and rotation speed result in low open circuit potential and high corrosion current density. The material loss was greater under open circuit potential than under cathodic protection. Corrosion induced an increase in material loss. The material loss caused by a synergistic effect between corrosion and wear contributed to about 20% of the total material loss. The synergistic effect can be divided into wear-induced corrosion and corrosion-induced wear. Wear-induced corrosion was caused by damage to the passive film due to the sliding action of the counterbody, leading to accelerated dissolution. Corrosion can promote the growth and propagation of microcracks in the wear track, which causes corrosion-induced wear.     

Tribological Performance of CuPb Alloy under Seawater Lubrication

In this article, the tribological behaviors of Cu–30wt% Pb (denoted as CuPb) alloy sliding against aluminum bronze ZCuAl9Mn2 lubricated by seawater were investigated. It was found that the friction coefficients decrease with increasing load and sliding speed, and the wear rates increase slightly with applied load but decrease with sliding speed. The low friction coefficient and wear rate can be attributed to the seawater as a lubrication medium, which has lubricating, cooling, and corrosive effects on the sliding couple.     

Wear of spray deposited Al–6Cu–Mn alloy under dry sliding conditions

The dry sliding wear of spray deposited Al–6Cu–Mn alloy was studied as a function of applied load in the range of 5–400 N. The variation of wear rate with applied load was obtained, from which four regions can be observed. On the basis of observations and analyses on the worn surface, the worn subsurface, the wear debris and friction coefficient, wear mechanism in different regions has been identified. Two wear regimes, i.e. mild and severe wear, were displayed in the entire applied load range. The transition from mild to severe wear occurred at a critical load. Mild wear involves three regions in the wear rate vs. load variation, and the wear in each region was controlled by different wear mechanism. With increasing load, the dominant wear mechanism in the period of mild wear displays successively oxidative wear, delamination and subsurface-cracking assisted adhesive wear. Severe wear was operated by the adhesive wear mechanism and the wear debris was formed by the shear fracture of subsurface material of the pin. The transition from mild to severe wear depended on the strength of the material of the pin adjacent to the contact surface and the strain-induced shear stress created by applied load.     

Effect of sodium octanoate on the tribocorrosion behaviour of 5052 aluminium alloy

ABSTRACT

The 5000 series aluminium alloys are commonly used in a marine application where it is exposed to environments containing the chloride ions, which cause corrosion of aluminium alloy. The situation becomes even worse when aluminium alloys, in some situations, may suffer from combined corrosion and wear actions. The present study has been carried out to investigate the effect of sodium octanoate as a corrosion inhibitor on the corrosive wear behaviour of aluminium alloy 5052 in 0.5?M NaCl solution as simulated seawater. The effects of electrochemical potentials on the corrosive wear performance are also discussed.     

Micro-abrasion resistance of thermochemically treated steels in aqueous solutions: Mechanisms, maps, materials selection

The area of micro-abrasion is an interesting and relatively recent area in tribo-testing methodologies, where small particles of less than 10 μm are employed between interacting surfaces. It is topical for a number of reasons; its direct relation to the mechanisms of the wear process in bio-tribological applications, ease in conducting tests and the good repeatability of the test results. It has widespread applications in conditions used in the space and offshore industries to bio-engineering for artificial joints and implants.There have been many recent studies on the micro-abrasion performance of materials, ranging from work basic metals to nano-structured coatings. However, no significant work is reported on the micro-abrasion resistance of thermochemically treated steels. Hence, this paper looks at the performance of two thermochemically treated steels, Tenifer bath nitride stainless steel (T-SS) and vanadized carbon steel (V-CS) in such conditions with reference to the stainless steel (SS) by varying the applied load and sliding distance.The results indicated that T-SS demonstrates exceptionally poor resistance to micro-abrasion. It was observed that the heat treatment process and properties of the hardened layer (hardness and thickness) are extremely important in determining the micro-abrasion resistance of such steels. Finally, the results were used to develop micro-abrasion mechanism and wastage maps, which can be used to optimize the surface treated materials for micro-abrasion resistance.     

Micro-abrasion mechanisms of cast CoCrMo in simulated body fluids

The abrasion seen on some of the retrieved CoCrMo hip joints has been reported to be caused by entrained hard particles in vivo. However, little work has been reported on the abrasion mechanisms of CoCrMo alloy in simulated body environments. Therefore, this study covers the mapping of micro-abrasion wear mechanisms of cast CoCrMo induced by third body hard particles under a wide range of abrasive test conditions. This study has a specific focus on covering the possible in vivo wear modes seen on metal-on-metal (MoM) surfaces. Nano-indentation and nano-scratch tests were also employed to further investigate the secondary wear mechanisms—nano-scale material deformation that involved in micro-abrasion processes. This work addresses the potential detrimental effects of third body hard particles in vivo such as increased wear rates (debris generation) and corrosion (metal-ion release). The abrasive wear mechanisms of cast CoCrMo have been investigated under various wear-corrosion conditions employing two abrasives, SiC (4 μm) and Al₂O₃ (1 μm), in two test solutions, 0.9% NaCl and 25% bovine serum. The specific wear rates, wear mechanisms and transitions between mechanisms are discussed in terms of the abrasive size, volume fraction and the test solutions deployed. The work shows that at high abrasive volume fractions, the presence of protein enhanced the wear loss due to the enhanced particle entrainment, whereas at much lower abrasive volume fractions, protein reduced the wear loss by acting as a boundary lubricant or rolling elements which reduced the abrasivity (load per particle) of the abrasive particles. The abrasive wear rate and wear mechanisms of the CoCrMo are dependent on the nature of the third body abrasives, their entrainment into the contact and the presence of the proteins.     

Sliding wear of TiC–NiMo cermets

The friction and wear properties of TiC–NiMo/steel rubbing pairs were investigated under dry condition. The sliding wear tests were carried out on the testing device at a velocity of 2.2 m/s and a load of 40 N. The volume wear increases with increase of the sliding distance as predicted by Archard’s equation. The wear coefficient of the cermets reduces with the increase of TiC and Mo content in the composite. The study has shown that the coefficient of friction was approximately the same for all the samples. The main wear mechanism in the TiC–NiMo cermets was micro-abrasion (polishing) and adhesive wear. At the initial stages of wear, adhesive wear characteristics featured by mild scratching and plastic smearing were observed on the worn surface, but at the later stages, contact fatigue failure of a relatively thick surface layer takes place.     

Tribocorrosion in implants—assessing high carbon and low carbon Co–Cr–Mo alloys by in situ electrochemical measurements

Tribocorrosion is defined as the chemical–electrochemical–mechanical process leading to degradation of materials in tribological contact immersed in a corrosive environment. Degradation results from the combined action of corrosion and mechanical loading and it is well-known that synergistic effects can accentuate the wear–corrosion rate. While the role of lubrication in reducing wear has been identified, there are still some key unanswered questions in relation to the importance of wear/corrosion interactions. In this study in situ electrochemical measurements have been made to isolate corrosion and corrosion-enhanced wear/tribology damage mechanisms on high carbon CoCrMo and low carbon CoCrMo alloys. Tests are carried out in three different biological solutions: 50% calf bovine serum, Dulbecco's Modified Eagle's Medium (DMEM) and 0.36% NaCl solution at 37 °C with the specific objective being to attempt to isolate the effects of proteins and amino acid species in wear–corrosion. In this paper, a detailed analysis of corrosion/wear interactions is presented, which facilitates discussion of exactly how corrosion and wear processes interact and the role of the lubricating fluid in this respect.