Papers by Keyword: Wear

Abstract: WC/Co; Composite coating; Plasma spraying; Friction and wear Abstract: WC- Co composite powders were synthesized by direct mechanical grinding in a rotary-vibration mill under 8h, and then analyzed by SEM and XRD. WC and WC/Co composite coatings were prepared by supersonic plasma spraying fine WC-Co composite powders. The wear and friction properties of both coatings were evaluated. The results showed that the wear resistance of the WC/Co composite coating was superior to that of the WC coating. The improvement in wear resistance of the WC/Co composite coating was attributed to its higher fracture toughness and adhesion strength as well as better thermal diffusivity. As for the WC/Co composite coating, the mechanism was mainly adhesion with micro-abrasion and fatigued-induced brittle fracture within splats, and the delamination along splat boundaries only occurred at high load. However, the failure of the WC coating was predominantly detachment of transferred film and brittle fracture within the splats and delamination along splat boundaries, which were enhanced with the increasing load.

Abstract: Thermal spray technology allows providing wear-resistant coating on the surface of mechanical components. In this study, wear characteristics of thermally sprayed Al/SiC composite coatings were evaluated. These Al/SiC composite coatings reinforced with SiC particles were fabricated on Al 6061 substrate by thermal spray process. Dry sliding wear tests were performed using the varied sliding speeds and applied loads. Wear behavior of these Al/SiC composite coatings were investigated using scanning electron microscope(SEM), energy dispersive X-ray spectroscopy(EDX) and X-ray diffraction(XRD).

Abstract: The performance curves of a submersible axial flow pump were predicted based on mixture multiphase flow model, RNG k-ε turbulence model and SIMPLEC algorithm, and the solid-liquid two-phase flow in the impeller was simulated. The numerical results show that the performance prediction of the head and efficiency curves show good agreement with the experimental data in the whole flow rate range, and the solid particles in the impeller are mainly distributed on pressure side of blades, while less on the suction side.The solid particles are mainly concentrated in the blade inlet and region near the hub of the pressure side. The experimental results also show that the blade pressure sides have serious erosion, particularly near the hub, but less wear and tear on the suction side.The accuracy of the numerical simulation results are verified by the experiments.

Abstract: The slipper pairs with concaves of reasonable and unreasonable structures and without concave originally are chosen for the experiment. The experimental results show that appropriate concave distribution can improve the wear and tear condition of the slipper bottom. Under the same experimental condition, the fringe wear volume can be reduced by 28.77%, and the overall wear volume 68.72%, which is the best result.

Abstract: Different techniques have been developed in the area of bearing wear monitoring. This paper proposes a different experimental study on bearing wear monitoring by using an airborne technique. The data captured in the airborne technique will be analyzed by using I-kaz^TM Multi Level (⁷Z) coefficient and then will be correlated with the conventional specific wear rates, K. The wear tests were carried out by using a pin-on-disc configuration at a sliding speed of 7.85 m/s. A set of sliding distance ranging from 20 160 km at a fixed load of 200 N was utilized and the K value was measured at every interval of 20 km for the speed. SAE40 type lubricant was used in the test to simulate the actual operation of the connecting rod bearing. The audio range frequency below 20 kHz in the airborne technique was obtained through a microphone 40SC type which was placed 10 mm from the pin-disc contact. The analysis result showed that the wear rate, K increased from 1.82 to 6.70x10^-8 mm³/Nm as the sliding distance increased, indicating that a mild-abrasion wear regime had occurred. The curve fitting of K as a function of I-kaz^TM Multi Level coefficient showed a similarity to an established of Taylor Tool Life curve. Thus, it was possible to correlate the Taylor curve and worn bearing, mainly in monitoring and identifying the bearing condition with respect to the sliding distance. The trend of I-kaz^TM Multi Level coefficient was found to be consistent with the increase of sliding distance which indicates that the I-kaz^TM Multi Level value can positively be used as wear response indicator for bearing.

Abstract: In the present investigation, the surface of a commercially pure titanium (CP-Ti) substrate was modified to Ti/SiC nanocomposite layer employing friction stir processing technique; nanosized SiC powder was introduced into the stir zone provided by a rotating and advancing tool. The fabricated nanocomposite surface layer exhibited a micro hardness value of ~535HV which is much greater than 160HV of the substrate material using Vickers micro hardness testing. In addition, the un-treated CP-Ti substrate showed sever wear regime in the pin-on-disc test against the hardened AISI 52100 steel. It suffers extensive typical adhesive wear dominated by plastic deformation as evidenced by scanning electron microscopy. Also, deep grooves were formed, i.e. evidence of abrasive wear. Contrary to this, enhanced wear properties were detected for the Ti/SiC nanocomposite surface layer, i.e. lower coefficient of friction and weight loss. The nanocomposite surface layer was found to be adherent to the underlying substrate during the pin-on-disc test. The superior wear behavior of the nanocomposite surface layer is attributed to its improved micro hardness value due to the presence of hard nanosize SiC particles in a refined titanium matrix.

Abstract: Wear study of metal matrix composites used as friction material is one of the most important parameter for determining the brake performance. The present investigations relates to the development of Aluminum powder based brake pads; where the back plates are also made of Aluminum based powders respectively. Thus it is aimed to fabricate net-shape Aluminium powder based brake pads in a single forming operation with better characteristics (low wear, low temperature rise, stable coefficient of friction) employing a newly developed technology namely “Hot Powder Preform Forging” technique. Three Aluminum based friction composites which are designated as ALM 01, ALM 02 & ALM 03 were formulated. The dry wear test is carried out using a pin-on-disc tribo-tester at constant sliding speed of 9 ms-1 under a load of 50 N. The counter face disc is made of heat treated grey cast iron. During the test, the cumulative wear (gm), Coefficient of friction, temperature rise (oC) and noise level (dB) were recorded. The effect of load at constant speed on sliding wear, frictional characteristic of aluminum based MMC (rotor / drum) in dry condition is studied. On the basis of initial laboratory tests like density, Hardness, wear test, the samples were qualified for sub-scale dynamometer test at Rejected Take Off condition. Optical microscope was used to investigate the microstructure of metal matrix friction composites surfaces. The results revealed that coefficient of friction was more stable. The Cumulative wear (gm) was low with rise in temperature. It was also observed that distribution of ingredients in matrix was fine and homogeneous.

Abstract: In the present study, the effect of microstructure on the wear characteristics of spray cast Al-15Si and Al-20Si alloys has been investigated and compared with that of vertical axis centrifugal cast and chill cast alloys. The spray cast alloys have been subjected to Hot Isostatic Pressing for porosity reduction. HIPing has reduced the porosity in the spray cast Al-15Si and Al-20Si alloys from 19% to 8% and 19% to 2% respectively. The microstructures of spray cast alloys consisted of finely divided globular shaped Si particles with sizes varying from 2–10 µm. The Si particles have been distributed uniformly throughout the Al matrix. On the contrary coarse and segregated microstructures have been observed in vertical axis centrifugal cast and chill cast alloys. The sizes of primary and eutectic Si in vertical axis centrifugal cast alloys are smaller than that in chill cast alloys. The wear rates are the lowest for spray cast alloys and highest for chill cast alloys over a wide range of sliding velocity. The reasons for better wear resistance of spray cast alloys have been discussed in the light of the microstructural features evolved during spray casting.

Abstract: An ANN BP model is built to imitate the relative between output, the wear of hobbing cutter, and input, such as rotary speed of cutter, air flow, air jet speed, air temperature, situation of hobbing cutter and hardness of work piece. A program is compiled to extrapolate the total life of hobbing cutter based on the BP model. The conclusion can be obtained by the program about the total life of hobbing cutter in cryogenic cutting with MQL, as follow. When parameters vary in the given zone, air jet speed has the largest effect on the total life of hobbing cutter by 23.8%, and follows the air flow by 13.5%, and last is the air temperature by 4.4%.

Abstract: To improve the wear property of 00Cr13Ni4Mo hydro turbine blade stainless steel, Ni-based composite coatings were fabricated on 00Cr13Ni4Mo stainless steel by laser cladding using mixed powders of Ni60, WC and TiN. The microstructure of the coatings was characterized by XRD and SEM techniques. The wear resistance of the coatings was evaluated under dry sliding wear condition at room temperature. The results show that the coatings mainly consist of Ni-based solid solution, WC and TiN phases. The coatings exhibit excellent wear resistance due to its high hardness of WC and TiN phases. The main wear mechanisms of the coatings and the 00Cr13Ni4Mo sample are different, the former is abrasive wear and the latter is adhesive wear.