The present work studies the tribological properties of new hybrid material composed from high porosity open cell aluminum alloy (AlSi10Mg) skeleton and B83 babbitt infiltrated into it. The porous skeleton is obtained by replication method applying salt (NaCl) as space holder. The reinforcing phase of the skeleton consists of Al2O3 particles. The skeleton contains Al2O3 particles as reinforcement. The microstructure of the obtained materials is observed and the tribological properties are determined. A comparison between tribological properties of nominally nonporous aluminum alloy, high porosity open cell skeleton, babbitt alloy and the hybrid material is presented. It is concluded that new hybrid material has high wear resistivity and is a promising material for sliding bearings and other machine elements with high wear resistivity.

The paper presents the properties of surface oxide layers with an increased content of carbon for tribological applications. The composite surface oxide layers were produced using a two-step technology through hard anodising of the surface of an aluminium alloy, followed by thermochemical treatment of anodic oxide coatings. The surface oxide layers were subjected to tribological tests in an oil-less sliding couple with T5W plastic. The presented test results confirm the usefulness of the proposed modifications of surface oxide layers for the purpose of enhancing the operational durability of oil-less sliding couples in a reciprocating motion.

Among the family of stainless steels, cast austenitic stainless steels (CASSs) are preferably used due to their high mechanical properties

and corrosion resistance. These steels owe their properties to their microstructural features consisting of an austenitic matrix and skeletal

or lathy type δ-ferrite depending on the cooling rate. In this study, the solidification behavior of CASSs (304L and 316L grades) was

studied using ThermoCalc software in order to determine the solidification sequence and final microstructure during cooling. Theoretical

findings were supported by the microstructural examinations. For the mechanical characterization, not only hardness measurements but

also tribological studies were carried out under dry sliding conditions and worn surfaces were examined by microscopy and 3D

profilometric analysis. Results were discussed according to the type and amount of microstructural features.

AISI 52100 bearing steels are commonly used in applications requiring high hardness and abrasion resistance. The bearing steels are

working under dynamic loads in service conditions and their toughness properties become important. In order to provide the desired

mechanical properties, various heat treatments (austenizing, quenching and tempering) are usually applied. In this study, AISI 52100

bearing steel samples were austenized at 900°C for ½ h and water quenched to room temperature. Then tempering was carried out at

795°C, 400°C and 200°C for ½ h. In order to investigate the effect of heat treatment conditions on wear behavior, dry friction tests were

performed according to ASTM G99-05 Standard with a ‘ball-on-disk’ type tribometer. The samples were tested against steel and ceramic

counterparts using the parameters of 100 m distance and 30 N load and 0.063 m/s rotational speed. After wear test, the surface

characterization was carried out using microscopy. Wear loss values were calculated using a novel optical method on both flat and

counterpart specimens.

Emergence of new designs for internal combustion engines resulted in a necessity to search for new materials which will rise to excessive technological requirements under operating conditions of modern internal combustion engines of up to 150 kW. Focusing only on material properties, theoretically existing alloys should meet presents requirements. More importantly, existing materials are well fitted to the entire crank-piston system. Thus, there is a need for a more thorough examination of these materials. The paper presents studies on determination of coefficient of friction μ and wear for the A390.0 alloy modified with AlTi5B master alloy combined with EN GJL-350 cast iron. The characteristics of a T-11 tribological tester (pin on disc) used for the tests, as well as the methodology of the tribological tests, were described. Also, the analysis of the surface distribution of elements for the pin and the disc was presented. The studies were realized in order to find whether the analyzed alloy meets the excessive requirements for the materials intended for pistons of modern internal combustion engines. The results show that the A390.0 alloy can only be applied to a load of 1.4 MPa. Above this value was observed destructive wear, which results in the inability to use it in modern internal combustion engines.

The paper presents the influence of modification with phosphorus (CuP10) on the tribological properties of the alloy AlSi17Cu5Mg coupled

abrasively with cast-iron EN GJL-350. Tests of coefficient of friction and wear of mass were conducted on tribological tester T-01. An

important aspect in the assessment of the tribological properties is the analysis of initial material microstructure in reference to silumin which

underwent modification with phosphorus. It was found that the difference in structure of tested materials, mainly sizes of primary silicon

crystals significantly influences the tribological properties whereas the speed change of the friction knot does not have such big influence.

Mechanical components and tools in modern industry are facing increasing performance requirements leading to the growing need for advanced materials and thus, for modern frictional systems. In the last decades, the Pulsed Laser Deposition (PLD) has emerged as an unique tool to grow high quality mono- as well as multilayers surfaces in metallic/ceramic systems. Building up a knowledge base of tribological properties of industrially-scaled, room temperature deposited PLD hard coatings are the most important step for the application of these coatings in engineering design. Although single-layer coatings find a range of applications, there are an increasing number of applications where the properties of a single material are not sufficient. One way to surmount this problem is to use a multilayer coating. Application of metallic interlayers improves adhesion of nitride hard layer in multilayer systems, which has been used in PVD processes for many years, however, the PLD technique gives new possibilities to produce system comprising many bilayers at room temperature. Tribological coatings consisted of 2, 4 and 16 bilayers of Cr/CrN and Ti/TiN type were fabricated with the Pulsed Laser Deposition (PLD) technique in the presented work. It is found in transmission electron examinations on thin foils prepared from cross-section that both nitride-based multilayer structures studied are characterized by small columnar crystallite sizes and high defect density, what might rise their hardness but compromise coating adhesion. The intermediate metallic layers contained larger sized and less defective columnar structure compared to the nitride layers, which should improve the coatings toughness. Switching from single layer to multi-layer metal/nitride composition improved resistance to delamination.

The purpose of the present paper was to investigate the effect of shot peening on the condition of the surface layer and abrasion resistance of specimens made of Ti-6Al-4V titanium alloy produced by Direct Metal Laser Sintering (DMLS) process. The specimens have been produced by means of EOSINT M280 system dedicated for laser sintering of metal powders and their surfaces have been subjected to the shot peening process under three different working pressures (0.2, 0.3 and 0.4 MPa) and by means of three different media i.e. CrNi steel shot, crushed nut shells and ceramic balls. The specimens have been subjected to profilometric analysis, to SEM examinations, microhardness tests and to tribological tests on ball-on-disc stand in Ringer fluid environment. The general results of all tests indicate to favourable effect of shot peening process on the hardness and tribological performance of titanium alloy.

Nowadays, Aluminium (Al) based hybrid surface composites are amongst the fastest developing advanced materials used for structural applications. Friction Stir Processing (FSP) has emerged as a clean and flexible solid-state surface composites fabrication technique. Intensive research in this field resulted in numerous research output; which hinders in finding relevant meta-data for further research with objectivity. In order to facilitate this research need, present article summarizes current state of the art and advances in aluminium based hybrid surface composites fabrication by FSP with in-situ and ex-situ approach. Reported literature were read and systematically categorized to show impacts of different types of reinforcements, deposition techniques, hybrid reinforcement ratio and FSP machine parameters on microstructures, mechanical and tribological characteristics of different Al alloys. Challenges and opportunities in this field have been summarized at the end, which will be beneficial to researchers working on solid state FSP technique.

What is the limit of improvement the structure obtained directly from the liquid state, with possible heat treatment (supersaturation and aging)? This question was posed by casting engineers who put arbitrary requirements on reducing the DAS (Dendrite Arm Spacing) length to less than a dozen microns. The results of tests related to modification of the surface microstructure of AlSi7Mg alloy casting treated by laser beam and the rapid remelting and solidification of the superficial casting zone, were presented in the paper. The local properties of the surface treated with a laser beam concerns only a thickness ranging from a fraction to a single mm. These local properties should be considered in the aspect of application on surfaces of non-machined castings. Then the excellent surface layer properties can be used. The tests were carried out on the surface of the casting, the surface layer obtained in contact with the metal mould, after the initial machining (several mm), was treated by the laser beam. It turned out that the refinement of the microstructure measured with the DAS value is not available in a different way, i.e. directly by casting. The experimental-simulation validation using the Calcosoft CAFE (Cellular Automaton Finite Element) code was applied.

Deep cryogenic treatment (DCT) is gaining popularity as a treatment used to modify structures obtained during heat or thermo-chemical treatment. The article presents the influence of DCT, carried out during heat treatment before and after gas nitriding processes, on the formation of gas nitrided layers on X153CrMoV12 steel. It was found that the use of DCT between quenching and tempering performed prior to gas nitriding processes, increases the hardness, thickness and wear resistance of the nitrided layers. At the same time, if we apply cryogenic treatment during post-heat treatment of nitrided layers, we also get very high wear resistance and increased thickness of nitrided layers, in comparison with conventional gas nitriding of X153CrMoV12 steel. In this case, DCT significantly increases also the hardness of the core by the transformation of retained austenite and the precipitation of fine carbides of alloying elements.

In this study, AZ91 Magnesium alloy is produced by cold chamber high pressure die casting (HPDC) method. Different combinations of the cold chamber HPDC process parameters were selected as; in-mold pressure values of 1000 bar and 1200 bar, the gate speed of 30 m/s and 45 m/s, the casting temperatures of 640°C and 680°C. In addition, the test samples were produced by conventional casting method. Tensile test, hardness test, dry sliding wear test and microstructure analysis of samples were performed. The mechanical properties of the samples produced by the cold chamber HPDC and the conventional casting method were compared. Using these parameters; the casting temperature 680°C, in-mold pressure 1000 bar and the gate speed 30 m/s, the highest tensile strength and the hardness value were obtained. Since the cooling rate in the conventional casting method is slower than that of the cold chamber HPDC method, high mechanical properties are obtained by the formation of a fine-grained structure in the cold chamber HPDC method. In dry sliding wear tests, it was observed that there was a decrease in friction coefficient and less material loss with the increase of hardness values of the sample produced by the cold chamber HPDC method.