Enhanced Mechanical and Tribological Capabilities of a Silicon Aluminum Alloy with an Electroplated Ni–Co–P/Si3N4 Composite Coating

Ni–Co–P/Si3N4 composite coatings were fabricated over an aluminum–silicon (Al–Si) substrate using a pulse-current electroplating process, in which the rapid deposition of an intermediate nickel–cobalt layer was used to improve coating adhesion. The microstructure, mechanical, and tribological behaviors of the electroplated Ni–Co–P/Si3N4 composite coating were characterized and evaluated. The results revealed that the electroplated Ni–Co–P/Si3N4 composite coating primarily consisted of highly crystalline Ni–Co sosoloid and P, and a volumetric concentration of 7.65% Si3N4. The electroplated Ni–Co–P/Si3N4 composite coating exhibited hardness values almost two times higher than the uncoated Al–Si substrate, which was comparable to hard chrome coatings. Under lubricated and dry sliding conditions, the electroplated Ni–Co–P/Si3N4 composite coating showed excellent anti-wear performance. Whether dry or lubricated with PAO and engine oil, the composite coating showed minimum abrasive wear compared to the severe adhesive wear and abrasive wear observed in the Al–Si substrate.

Thermal Treatment of Carbidostals TiC – I2XI8H10T

An important task of thermal treatment of carbidostals having different composition of titanium carbide and steel I2XI8H10T is the possibility of improving their strength properties during operation under abrasive wear conditions. This question is new and little studied.

Failure analysis of excavator hydraulic pump

Hydraulic pump failures may be related to hardware or problem in oil. In this study, the excavator hydraulic pump failures were investigated by using visual observed and measuring the part component. The disassembled process of the pump was performed considering the manual part book of the excavator hydraulic pump. The abrasive wear on the pump slipper and swash plate was observed by comparing the guidelines for the reusable part. The value of more than 1.07 mm clearance within piston and cylinder bore was measured then the results over the allowable limit considering the manual part book. Properly analyzing of component failure can provide valuable information about what caused the failure and thus can be to avoiding future unscheduled downtime.

Experimental and Numerical Studies of Tool Wear Processes in the Nibbling Process

The work concerns an analysis of the wear mechanisms of punches in the nibbling process. The nibbling process is the multiple punching of holes or external contours using circular punches, the diameter of which is much smaller than the size of the punched shapes. Analytical, numerical and experimental studies were carried out. In the analytical solution, formulas for determining the pressures in the contact zone were developed, thus enabling a simple estimation of the designed nibbling tools. In numerical studies, the influence of the punch rounding radius on the fatigue wear was investigated. It has been shown that the change in the punch cutting edge radius from r = 0 mm to r = 0.5 mm enables a seven-fold increase in the fatigue wear resistance. It was found that the change in the punch cutting edge rounding radius has an impact on the quality of the product (the greater the radius r, the worse the technological quality of the product). In experimental studies, the abrasive wear process was primarily investigated. For this purpose, the nibbling process was tested on S235JR + AR steel sheets with tools made of NC11LV/1.2379 steel without any coating and with an AlCrTiN layer. It was found that the special AlCrTiN layer used allowed for an increase in the resistance to abrasive wear, and thus increased the service life by approx. three times. The last element of the work is an assessment of the technological quality of the product after nibbling depending on the degree and type of stamp wear (quantitative and qualitative assessment).

Influence of ultrasonic agitation on the abrasive wear characteristics of Al-Cu/ 2 vol.% Grp composite

In the present study, the abrasive wear behavior of Al-4.4 wt.% Cu composite reinforced with 2 vol.% graphite particle (Grp) has been investigated. In the preparation of composite, Ultrasonic Treatment (UT) is provided in the composite melt for the uniform distribution of reinforcement particles. Two bond abrasive wear tests are conducted for composites treated with ultrasound and without UT and base alloy. The results of abrasive wear studies indicate that at 5 and 10 Newton (N) loads, the composite with UT has a higher coefficient of friction (COF) and wear resistance than that of the base alloy (Al-4.4 wt.% Cu). Whereas, at 15 and 20 N load, the value of COF and wear resistance is lower for the composite. Two abrasive wear mechanisms micro-plowing and micro-cutting have been observed during the wear tests of base alloy and composites. The analysis of worn-out sample surfaces at higher load reveals that softened material layer due to localized elevation in temperature between two contact surfaces during wearing acts as a tribolayer in base alloy while in composites both softened material layer and graphite layer have worked together as tribolayer.