Erosion Wear Rate Research Articles

A model for the erosive wear of rubber at oblique impact angles

A model has been developed to predict the erosive wear behaviour of elastomers under conditions of glancing impact by small hard particles. Previous work has shown the erosive wear mechanism of elastomers under these conditions to be similar in nature to that of abrasive wear by a sharp blade. The model presented here was developed from the model of Southern and Thomas for sliding abrasion, by combining their treatment of the growth of surface cracks with a model for particle impact in which the force - displacement relationship for an idealized flat-ended punch on a semi-infinite elastic solid was assumed. In this way an expression for the erosive wear rate was developed, and compared with experimental measurements of wear rate for natural rubber, styrene - butadiene rubber and a highly crosslinked polybutadiene rubber. Good qualitative agreement was found between the predictions of the model and the experimental measurements. The variation of erosion rate with impact velocity, impact angle, particle size, elastic modulus of the material, coefficient of friction and fatigue properties were all well accounted for. Quantitative agreement was less good, and the effects of erosive particle shape could not be accounted for. The reasons for these discrepancies are discussed.

Corrosive wear behaviour of 304-L stainless steel in 1 N H 2SO 4 solution part 2. Effect of chloride ion concentration

Results on the influence of chloride ion levels on the corrosive wear rate of 304-L stainless steel in 1 N H 2SO 4 are discussed. The corrosive wear rate was measured at two different applied potentials: 200 and 600 mV ( vs. a saturated calomel electrode (SCE)). At an applied potential of 200 mV(SCE) the corrosive wear rates increased linearly with increasing chloride ion concentration from 0 to 23.4 g l −1. At 600 mV(SCE) the corrosive wear rates showed an increase similar to those at 200 mV(SCE) below the critical chloride ion concentration necessary for the occurrence of pitting. In addition, potentiokinetic, inductively coupled plasma spectroscopy, a.c. impedance, current decay transient, and scanning electron microscopy measurements were carried out. It is suggested that the increase in corrosive wear rate in the presence of chloride ions is caused by the decrease in current efficiency for the formation of a passivating oxide film caused by the presence of chloride ions.

Corrosive wear behaviour of 304-L stainless steel in 1 N H 2SO 4 solution Part 1. Effect of applied potential

The influence of applied potential on the corrosive wear rate of 304-L stainless in 1 N H 2SO 4 solution was studied using a modified pin-on-disc type wear machine. The corrosive wear rate increased with increasing applied potential up to 600 mV ( vs. a saturated calomel electrode (SCE)), and then decreased. The corrosive wear rate W CW consists of three factors: pure mechanical wear loss w MECH , weight loss caused by the corrosion reaction W DISS , and acceleratory contribution due to the presence of passivating oxide film W ACC . The relative fraction of the acceleratory contribution increased with increasing applied potential up to 200 mV(SCE), and then decreased. In order to investigate the role of the passivating oxide film in the corrosive wear process, potentiokinetic measurements, inductively coupled plasma spectroscopy, and scanning electron microscopy were carried out. From the results of such experiments, the variations of corrosive wear rate and acceleratory contribution associated with the applied potential are discussed in terms of competing of the corrosion reaction and compositional change in the passivating oxide film.

Effect of the Fracture Toughness of Impact Particles on the Erosive Wear of Ceramics.

The effect of the fracture toughness of impact particles on the erosive wear of ceramics was examined. Six kinds of Al2O3 abrasive particles, which were almost the same in size, figure and hardness, but different only in fracture toughness, were used as impact particles. Sintered Si3N4, Al2O3 (HA9O) and glass were used as target materials. Irrespective of the target materials, the erosive wear rate was qualitatively proportional to the fracture toughness of the impact particles.

セラミックスのエロージョン摩耗に及ぼす衝突粒子の靭性の効果

The effect of the fracture toughness of impact particles on the erosive wear of ceramics was examined. Six kinds of Al2O3 abrasive particles, which were almost the same in size, figure and hardness, but only different in fracture toughness were used as impact particles. Sintered Si3N4, Al2O3 (HA90) and glass were used as target materials. Irrespective of the target materials, the erosive wear rate was qualitatively proportional to the fracture toughness of the impact particles.

セラミックスのサンドエロージョン―衝突速度と角度の効果

Erosive wear tests were carried out for nine specimen / particle pairs which were assorted three specimens, SiC, Si3N4 and glass with three particles, SiC, Al2O3, and glass, at the impact velocity (V) of 50-300m/s and at the impact angle(θ) of 20-80°. The value of n in the equation for the erosive wear rate (W), W∞Vn.sinθm, was (3.0-3.6) for all pairs. The value of m was (0.63-1.2) for the pairs of SiC and Si3N4 specimens with Al2O3, particle, and (1.4-1.8) for the other pairs. The difference in the m value was explained as the results of the difference in the erosive wear mechanism caused by the differences of the fracture toughness(KIc) between the specimens tested and the frangibility between the particles, used.

Corrosive Wear of Cast Iron in Sulphuric Acid

The wear rate of cast iron and the corrosion potential (Ecorr) and current (Icorr) were measured in sulphuric acid in order to study the mechanism of corrosive wear of cast iron. The corrosive wear rate of cast iron was found to reach a maximum at around 35 wt. percent sulphuric acid concentration and increase with load and acid temperature. The increment of corrosion current, i.e., the dissolution rate of Fe ion, due to friction (ΔIcorr) was found to correlate with the corrosive wear of cast iron. It has been concluded that the combined action of the changed properties and profile of corroded rubbing surfaces and the mechanical destruction due to wear causes the drastic corrosive wear, which is much greater than the wear seen with either one alone.

Erosion wear in slurry pumps and pipes

Erosion wear is an important factor in the design and operation of the equipment handling slurries. This paper outlines an energy approach to determine the erosion wear from the solids velocity and concentration distributions in the vicinity of the exposed walls. The worn material is assumed to be removed by one of the following mechanisms: directional impact, random collisions and Coulombic friction. Mechanistic and stochastic models provide the description of the wear mechanisms at the particle scale. The correlation between the energy dissipated by particle — wall mechanical interaction and erosion wear rate is verified on small-scale devices, which simulate each wear mechanism separately. A complex hydraulic loop system was built in laboratory to systematically test the approach (maximum pump power = 1500 kW, maximum flowrate = 10 4 m 3 /h, pipe diameters = 75 – 760 mm). Finite volume and finite element methods are used to numerically simulate the two-phase flow in pipes and pump components, with some simplifying assumptions. Experimental and computational results on fine particle (d ⩽ 0.5 mm) slurry wear in straight pipes and centrifugal pump casings are presented. The approach was applied to predict the wear distribution and operation life of sand slurry pipes, as well as dredging and ore-handling pumps.

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.

Erosive wear of composite materials

The erosive wear behavior of selected polymer matrix composite materials was investigated using an erosion wear tester. Scanning electron microscopy was used to characterize the eroded surface. The results show that the erosive wear rates in these materials are at least an order of magnitude greater than that of low carbon steel. Of the composites tested, continuous graphite fiber-epoxy composites showed erosive wear that is typical of brittle materials (maximum wear rate when the impingement is normal to the surface), while continuous aramid fiber-epoxy and chopped graphite fiber-polyphenylene sulfide showed quasi-ductile behavior (maximum wear rate at 25°–45° impingement angle). These results are discussed in terms of the observed failure modes.

鉱物粒子による材料の摩耗

A number of studies have recently been carried out in which the abrasive and erosive wear rate of the materials by the mineral grains was determined. In this paper the effects of various variables on these wear are summarized.M ain contents are as follows:1) Introduction: Difinition of wear, Classification of wear testing methods- three-body sliding friction between loose mineral grains and materials (flat-flat plate and flat-circle plate), two-body sliding friction between materials and minerals (fixed and loose abrasive), rolling and impacting between materials and loose mineral grains (ball or rod mills), rotating of materials in loose mineral grains, impacting of loose mineral grains against materials and impacting of materials against loose mineral grains-, Relations between different testing methods.2) Factors influencing abrasive and erosive wear: Knoop and micro Vickers hardness of minerals and materials, Correlationsbetween wear rate W and hardness ratio (material hardness Hm/mineral hardness Ha)-W∝(Hm/Ha) n-, Wear-resistant factors except hardness- Youngs modulas, tensile strength, fatigue strength, impact strength, etc.-, Effect of mineral grains size while the wear rate are proportional to the grain size, after the critical size (about 10-300 pm) it is almost constant-.3) Wear characteristics: Initial and steady wear processes-in steady wear the wear rate are proportional to sliding distance or impact time-, Influence of velocity V-W∝ Vn, where n value are 0-0.5 in two and three-body sliding friction testing methods, 0.8-1.3 in ball mill, 2-6.5 in testing methods of impacting of loosegrains against materials (metal: 2-3 and non-metal: 3-6.5)-, Influence of impact angle in erosive wear-the ductile materials exhibits maximum wear rate at low impact angle, but the brittle materials produces its maximum at high angle (for example, rubber: 0°, steel: 15-25°, castiron: 40-50°, glass: 90°).

Untersuchungen an einem vierwalzen-kaltband-umkehrgerüst für weissblech

In order to improve the biomedical properties of a titanium alloy surface, electro-spark surface alloying was carried out using a graphite electrode in air, in a nitrogen gas atmosphere and in silicone oil. The morphology and microstructure of the strengthened layers were analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The hardness distributions as a function of depth were measured by a micro-hardness tester. Corrosion resistance capacities of the modified layers were evaluated using potentiodynamic polarization measurements and electrochemical impedance spectroscopy (EIS). In addition, wear resistance and corrosive wear properties in a simulated body fluid (SBF) were studied with a pin-on-disk tribometer. Alloyed layers, completely covering the substrate surface and about 40 μm thick mainly composed of the TiC phase and with strong metallurgical bonding and adhesion to the substrate, were obtained. This can markedly improve hardness and wear resistance of the surface layer of the substrate. In comparison to coatings prepared in air and nitrogen gas atmospheres, the coating produced in silicone oil media exhibits a denser and more perfect surface structure. The wear resistance in air and corrosive wear resistance in SBF solution is the best for the coating produced in silicone oil. For instance, the wear rate in air with a GCr15 steel ball counterpart is reduced by a factor of 29 compared with the original titanium alloy and the corrosive wear rate in SBF solution with a corundum ball can decrease by a factor of 13.8. Simultaneously, the effect of electron-spark surface alloying of the titanium alloy surface on biocompatibility and biological activity was also investigated. The electron-spark surface strengthened layer treated in silicone oil shows good biocompatibility and biological activity, and can help cell attachment to the substrate surface.