Search

FSW is a solid-state joining process. It is widely used for joining hard alloys like steel, titanium, and aluminium which are very difficult to join by fusion welding. FSW joint quality is mainly influenced by shoulder and pin geometry, its diameter, tool material, tool rotation speed, and linear traveling speed. The paper presents a brief overview of the tools used during the FSW procedure. The influence of the tool pin on the material flow and mixture was analysed in detail. In addition, the primary and secondary material flow and how it is affected by the shape and dimensions of the tool pin are also discussed.

The paper presents experimental testing of wear resistance of steel samples from the same groups of steel. Test results were recorded and presented in the form of diagrams showing the wear resistance of the tested materials in different sliding conditions. The tested steels have high carbon content; the addition of chromium and molybdenum results in the high hardness and low impact toughness of the steels. The addition of vanadium changes the microstructure when the metal grain becomes smaller and the whole structure is martensitic, with chromium and vanadium carbides in the metal matrix. A change in the microstructure causes a change in mechanical properties. The obtained results showed that the addition of vanadium increases impact toughness. However, it is not known how it affects wear resistance and hardness. This type of steel belongs to a new group of steels resistant to wear. A change in the vanadium content causes a decrease in the hardness and wear resistance of the steel and an increase in its impact toughness.

Mechanical and tribological investigation of obtained nanocomposites is presented in this paper. As matrix material, well known tribological zinc-aluminium alloy, ZA-27 was used. Nanocomposites were obtained by compocasting procedure, while as reinforcement Al2O3 nanoparticles with average size of 20-30 nm was used. Nanocomposites with three different volume fractions were obtained. In order to get insight in structure and mechanical properties of obtained nanocomposites density and hardness measurements were performed. Tribological properties of tested materials were investigated using block-on-disc tribometer in dry sliding conditions with variation three different values of sliding speed and normal load. Wear tracks that were generated as a result of dry sliding process were analysed using optical and scanning electron with EDS microscope.

The paper presents the methods for prediction of the cutting parameters. In order to test the workability of the material by process of scraping, from the aspect of the cutting temperature, an natural thermopar was placed just below the cutting edge of the plate. In this way, a simple, reliable, accurate and economical method for determining the workability of material by cutting is obtained. The feasibility study of several semi-finished products by applying the realized experiments was carried out. Different materials in processing with cutting discs with different coatings give different results, which are used to form neural network and linear regression models.

Transport is largely dependent on oil because the majority of transport vehicles are propelled by engines combusting petroleum products-hydrocarbon fuels. This particularly relates to road, air and water transport. Power losses in the internal combustion engines and other reciprocating machines are mainly engaged to overcome friction. If using aluminum alloys for producing of piston and cylinders in engines and compressors, the results are lower fuel consumption and exhaust emission, firstly because of lower weight and mechanical losses, too. The problems are poor tribological characteristics and lower strength of unprotected aluminum comparing with gray cast iron. For research purposes, the inner surface of cylinder which was produced of aluminum was reinforced by integrating tribological inserts. In this paper, the tribological properties of ferrous based reinforcements were analyzed and compared with aluminum alloy as a base material for cylinder liner and piston skirt in air brake compressor. The ball-on-plate CSM tribometer was used to carry out these tests under dry sliding conditions. In addition to tribological, have carried out and testing of experimental reciprocating compressor on the bench, in the laboratory for engines and compressors in Faculty of Engineering in Kragujevac.

The aim of this paper is to show wear properties of different types of filler metals aimed for hard facing and exploitation in dry condition. Testing of wear resistance is done in laboratory on prepared samples/models in order to simulate real exploitation conditions. Samples were made by hard facing of carbon steel using 4 different filler metals. Hard facing was done by using MMA welding method in three layers with enough height so samples could be made. After samples were made, the hardness and microstructure of all zones of hard facing were determined. Testing of wear resistance is done using block on disc contact on samples made from pure weld metal. As a parameter for estimates of the wear resistance of models it was used volume of worn material in mm3. Metallographic investigations and hardness measurements were used as additional parameter for drawing the conclusions.

The paper presents tribological behaviour of aluminium nanocomposite A356/SiC produced by the compocasting process with mechanical alloying preprocessing (ball milling). Tribological tests were performed on tribometer with block-on-disc contact geometry under lubricated sliding conditions. Influence of amount of silicon carbide reinforcement (0, 0.2, 0.3 and 0.5 wt.%) on wear rate was investigated in the following testing conditions: sliding speed of 0.25 and 1.0 m/s, normal load of 40 N and 100 N and at sliding distance of 1000 m. Analysis of worn surface of nanocomposites was performed by using SEM equipped with EDS.

Applying new technologies to reduce friction and wear in vehicles and equipment can minimize mechanical losses. This reduces power loss in internal combustion engines and reduces fuel consumption and emissions. Consumption of fuel energy can be reduced by the use of light metals, for example aluminum alloy, to produce vehicles and their aggregates and parts. In this case, the problem is poor tribological properties of those light weight metals, as well as the lower strength compared to the cast iron construction. For tribology research purposes, the contact surface of the aluminum cylinder of an experimental piston air compressor is reinforced with inserts of cast iron. The results of tribology research of the composite material are presented in the paper, explaining how parameters such as the sliding speed, contact time and contact area influence friction and wear of the material in relative tribological contacts, under constant normal force. The test procedures were performed on the ball-on-plate CSM® nanotribometer, in linear reciprocating sliding conditions with no lubricant. Material composition of the samples was determined using the Energy-Dispersive Spectroscopy. All measurements were realized at the Faculty of Engineering, University of Kragujevac.

A tribological system is a complex non-linear system composed of the elements that are connected structurally and functionally. The aim of this paper is to present an overview of artificial neural networks, its development and applications of neural networks in the prediction of tribological properties of dental glass ceramic using a newly measured ball-on-plate nanotribometer. The possibility of artificial neural networks application to solve complex nonlinear problems and to identify tribological characteristics of dental glass ceramic in terms of wear rate and coefficient of friction is presented.

Purpose The purpose of this study is to show which filler metal is the best for hard facing. Because the quality of the surface layer has a great influence on the working life of parts, the purpose was to extend the working life of parts exposed to intensive wear. The tested hard-faced models were made of low carbon steel to save the expensive base metal and to analyze the possibilities of extending the service life of existing structural parts. Design/methodology/approach Samples were prepared from plates hard faced with various filler metals. Samples were then subjected to experimental testing – testing of tribological properties and hardness and microstructure. Testing was done in conditions similar to real ones – with a sliding speed of 0.25, 0.5 and 1 m/s and with a load of 50, 75 and 100 N and in most rigorous dry conditions. Research was done by using a combination of experimental and theoretical approaches. Findings The paper shows the results of the experimental testing of four different filler metals aimed for hard facing of parts exposed to highly intensive wear. Results shown that CrWC 600 alloy is the most favorable filler metal for hard facing of parts such as those of construction mechanization and those subjected to intensive abrasive wear at stone mines. Practical implications All obtained results are real and fully applicable, as there is a huge industrial need for these types of technologies. With the application of these technologies, beside money savings, the working life of parts can be significantly extended. Originality/value The research presented in this paper was conducted because of the lack of results from this area in Serbia and because of the necessity for application of obtained results in companies for road maintenance and stone excavation in the region of Šumadija, Serbia.

The objective of this investigation is to assess the influence of graphite reinforcement on tribological behavior of ZA-27 alloy. The composite with 2 wt% of graphite particles was produced by the compocasting procedure. Tribological properties of unreinforced alloy and composite were studied, using block-on-disk tribometer, under dry and lubricated sliding conditions at different specific loads and sliding speeds. The worn surfaces of the samples were examined by the scanning electron microscopy (SEM). The obtained results revealed that ZA-27/graphite composite specimens exhibited significantly lower wear rate and coefficient of friction than the matrix alloy specimens in all the combinations of applied loads (F n ) and sliding speeds (v) in dry and lubricated tests. The positive tribological effects of graphite reinforcement of ZA-27 in dry sliding tests were provided by the tribo-induced graphite film on the contact surface of composite. In test conditions, characterized by the small graphite content and modest sliding speeds and applied loads, nonuniform tribo-induced graphite films were formed leading to the increase of the friction coefficient and wear rate, with increase of the sliding speed and applied load. In conditions of lubricated sliding, the very fine graphite particles formed in the contact interface mix with the lubricating oil forming the emulsion with improved tribological characteristics. Smeared graphite decreased the negative influence of F n on tribological response of composites, what is manifested by the mild regime of the boundary lubrication, as well as by realization of the mixed lubrication at lower values of the v/F n ratio, with respect to the matrix alloy.