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The paper investigates the cavitation erosion (CE) and sliding wear (SW) resistance of cold-sprayed Al/Al2O3 and Cu/Al2O3 composites and studies them in relation to a set of metallic materials such as aluminium alloy (AlCu4Mg1), pure copper (Cu110), brass (CuZn40Pb2) and stainless steel (AISI 304). The coatings were deposited on stainless steel by low-pressure cold spray (LPCS) using Al (40 wt.%) and Cu (50 wt.%) blended with Al2O3 (60 and 50 wt.%, respectively) feedstocks. CE resistance was estimated by the stationary sample method according to the ASTM G32 standard. The SW test was conducted using a ball-on-disc tester with compliance to the ASTM G99 standard. Results obtained for the LPCS coatings show that the Cu/Al2O3 coating exhibits a denser structure but lower adhesion and microhardness than Al/Al2O3. The Al/Al2O3 and Cu/Al2O3 resistance to cavitation is lower than for bulk alloys; however, composites present higher sliding wear resistance to that of AlCu4Mg1, CuZn40Pb2 and stainless steel. The CE wear mechanisms of LPCS composites start at the structural discontinuities and non-uniformities. The cavitation erosion degradation mechanism of Al/Al2O3 relies on chunk material detachment while that of Cu/Al2O3 initiates by alumina removal and continues as layer-like Cu-metallic material removal. CE damage of metal alloys relies on the fatigue-induced removal of deformed material. The SW mechanism of bulk alloys has a dominant adhesive mode. The addition of Al2O3 successfully reduces the material loss of LPCS composites but increases the friction coefficient. Coatings’ wear mechanism has an adhesive-abrasive mode. In both CE and SW environment, the behaviour of the cold-sprayed Cu/Al2O3 composite is much more promising than that of the Al/Al2O3.

Article citation info: (*) Tekst artykułu w polskiej wersji językowej dostępny w elektronicznym wydaniu kwartalnika na stronie www.ein.org.pl Żebrowski r, wAlczAk M, klepkA T, pAsierbiewicz k. effect of the shot peening on surface properties of Ti-6Al-4V alloy produced by means of DMls technology. eksploatacja i Niezawodnosc -Maintenance and reliability 2019; 21 ( 1): 46-53, http://dx.doi.org/10.17531/ ein.2019.1.6. remigiusz Żebrowski Mariusz wAlczAk Tomasz klepkA kamil pAsierbiewicz EffEct of thE shot pEEning on surfacE propErtiEs of ti-6al-4V alloy producEd by mEans of dmls tEchnology WpłyW nagniatania strumiEnioWEgo na WłaściWości EksploatacyjnE stopu ti-6al-4V uzyskanEgo tEchnologią przyrostoWą dmls* The state of the surface layer and biocompatibility are the key parameters contributing to successful implantation of prostheses such as bone implants which are now increasingly often produced by means of DMLS technologies. The analysis of these factors and proper selection of material are required in order to determine the most favourable technological parameters contributing to long term functioning in course of their presence in human body. Therefore, the purpose of the present paper is to investigate the effect of shot peening on the state of the surface layer and corrosion resistance of specimens made of Ti-6Al-4V titanium alloy produced in 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 based on ZrO 2 . It has been found that the process conditions i.e. working pressure in course of shot peening and proper selection of applied shot will make it possible to achieve the properties in modified material sufficient to ensure that assumed functions associated with the improvement of surface layer condition are invariable during required period in specified implant operation conditions. In such case, these factors have been determined in course of microhardness tests, evaluation of surface development degree as well as potentiodynamic tests. The increase of working pressure caused deteriorated corrosion resistance. Simultaneously, it has been found the corrosion resistance was most satisfactory for the surfaces modified by means of: ceramic balls based on ZrO 2 > crushed nut shells > CrNi steel shot correspondingly.

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This study discusses a quantitative fatigue evaluation of polymer–ceramic composites for dental restorations, i.e., commercial material (Filtek Z550) and experimental materials Ex-nano (G), Ex-flow (G). Their evaluation is based on the following descriptors: microhardness, scratch resistance, and sliding wear. In order to reflect factors of environmental degradation conditions, thermal fatigue was simulated with a special computer-controlled device performing algorithms of thermocycling. Specimens intended for the surface strength and wear tests underwent 104 hydrothermal fatigue cycles. Thermocycling was preceded by aging, which meant immersing the specimens in artificial saliva at 37 °C for 30 days. Microhardness tests were performed with the Vickers hardness test method. The scratch test was done with a Rockwell diamond cone indenter. Sliding ball-on-disc friction tests were performed against an alumina ball in the presence of artificial saliva. A direct positive correlation was found between thermocycling fatigue and microhardness. The dominant mechanism of the wear of the experimental composites after thermocycling is the removal of fragments of the materials in the form of flakes from the friction surface (spalling). Hydrothermal fatigue is synergistic with mechanical fatigue.

The resistance to cavitation erosion and sliding wear of stainless steel grade AISI 304 can be improved by using physical vapor deposited (PVD) coatings. The aim of this study was to investigate the cavitation erosion and sliding wear mechanisms of magnetron-sputtered AlTiN and TiAlN films deposited with different contents of chemical elements onto a stainless steel SS304 substrate. The surface morphology and structure of samples were examined by optical profilometry, light optical microscopy (LOM) and scanning electron microscopy (SEM-EDS). Mechanical properties (hardness, elastic modulus) were tested using a nanoindentation tester. Adhesion of the deposited coatings was determined by the scratch test and Rockwell adhesion tests. Cavitation erosion tests were performed according to ASTM G32 (vibratory apparatus) in compliance with the stationary specimen procedure. Sliding wear tests were conducted with the use of a nano-tribo tester, i.e., ball-on-disc apparatus. Results demonstrate that the cavitation erosion mechanism of the TiAlN and AlTiN coatings rely on embrittlement, which can be attributed to fatigue processes causing film rupture and internal decohesion in flake spallation, and thus leading to coating detachment and substrate exposition. At moderate loads, the sliding wear of thin films takes the form of grooving, micro-scratching, micro-ploughing and smearing of the columnar grain top hills. Compared to the SS reference sample, the PVD films exhibit superior resistance to sliding wear and cavitation erosion.

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Atmospheric plasma spray (APS) wear-resistant coatings are popular in mechanical designing for increasing the operation time of machine elements. APS enables the deposition of ceramic, metallic, and cermet coatings to ameliorate the effects of wear that cause most of the failures of machine elements. The aim of the paper was to investigate the influence of the coating thickness of TiO2-10 wt% NiAl on abrasive, sliding, and cavitation erosion resistance. Titania based coatings were deposited by means of APS onto a mild steel substrate using TiO2-10 wt% NiAl feedstock material. The coatings had thicknesses of approximately 50, 100, and 200 µm. The morphology and microstructure of the coatings were examined using a light optical microscope (LOM) and scanning electron microscope (SEM). The as-deposited surface topography and hardness of the coatings were determined. The porosity and thickness were evaluated by using quantities image analysis software. Cavitation erosion tests were performed according to ASTM G32 (vibratory apparatus) and ASTM G134 (cavitating liquid jet). Abrasive and sliding wear tests were conducted using a three body abrasive tester and ball-on-disc apparatus, respectively. Generally the thickest coating presents an increase in resistance to sliding wear and cavitation erosion over the thinnest cermet coating.