Sandwich panels are composites which consist of two thin laminate outer skins and lightweight (e.g., honeycomb) thick core structure. Owing to the core structure, such composites are distinguished by stiffness. Despite the thickness of the core, sandwich composites are light and have a relatively high flexural strength. These composites have a spatial structure, which affects good thermal insulator properties. Sandwich panels are used in aeronautics, road vehicles, ships, and civil engineering. The mechanical properties of these composites are directly dependent on the properties of sandwich components and method of manufacturing. The paper presents some aspects of technology and its influence on mechanical properties of sandwich structure polymer composites. The sandwiches described in the paper were made by three different methods: hand lay-up, press method, and autoclave use. The samples of sandwiches were tested for failure caused by impact load. Sandwiches prepared in the same way were used for structural analysis of adhesive layer between panels and core. The results of research showed that the method of manufacturing, more precisely the pressure while forming sandwich panels, influences some mechanical properties of sandwich structured polymer composites such as flexural strength, impact strength, and compressive strength.

The tribological performance of metalwork steel tools is of vital importance in both cold and hot working processes. One solution for improving metal tool life is the application of coatings. This paper investigates the differences in quantitative wear behavior and wear mechanisms between AlCrSiN-coated and bare steel K340 and five reference tool steels: X155CrVMo12-1, X37CrMoV5-1, X40CrMoV5-1, 40CrMnMo7 and 90MnCrV8. The investigated tool steels were heat-treated, while K340 was subjected to thermochemical treatment and then coated with an AlCrSiN hard film (K340/AlCrSiN). The hardness, chemical composition, phase structure and microstructure of steels K340 and K340/AlCrSiN were examined. Tribological tests were conducted using the ball-on-disc tester in compliance with the ASTM G99 standard. The tests were performed under dry unidirectional sliding conditions, using an Al2O3 ball as a counterbody. The wear factor and coefficient of friction were estimated and analyzed with respect to hardness and alloying composition of the materials under study. Scanning electron microscopy (SEM) observations were made to identify the sliding wear mechanisms of the analyzed tool steels and physical vapor deposition (PVD)- coated K340 steel. In contrast to the harsh abrasive–adhesive wear mechanism observed for uncoated tool steels, the abrasive wear dominates in case of the AlCrSiN. The deposited thin film effectively prevents the K340 substrate from harsh wear severe degradation. Moreover, thanks to the deposited coating, the K340/AlCrSiN sample has a coefficient of friction (COF) of 0.529 and a wear factor of K=5.68×10−7 m3 N−1 m−1, while the COF of the reference tool steels ranges from 0.70 to 0.89 and their wear factor ranges from 1.68×10−5 to 3.67×10−5 m3 N−1 m−1. The AlCrSiN deposition reduces the wear of the K340 steel and improves its sliding properties, which makes it a promising method for prolonging the service life of metalwork tools.

The paper is a report of the examination of the tribological wear characteristics of certain dental metal biomaterials. In the study, tests were undertaken on the following materials: 316L steel, NiCrMo alloy, technically pure titanium (ASTM-grade 2) and Ti6Al4V ELI alloy (ASTM-grade 5). The tribological tests were performed in artificial saliva to determine the coefficient of friction and wear factor; the traces of wear were then ascertained through SEM. The significance of variations in the wear factor, was subsequently assessed by the U Mann-Whitney test. The resistance to wear in the ball-on-disc test under in vitro conditions was observed for the tested materials in the following order: NiCrMo>316L>Ti6Al4V>Ti grade 2.

The purpose of this study was to assess the effect on selected mechanical properties, of adding recast materials to the NiCrMo alloy of newly produced castings. Three groups of dental alloy NiCrMo (trade named Remanium CS+) were prepared by mixing 50% new alloy to alloy remnants from previous castings. The specimens in the first casting group used 100% new alloy and served as control (C1). The second group consisted of equal amounts of new alloy and alloy remnants cast only once (C2). The third group contained 50% of new alloy and alloy cast twice (C3). Microstructural analysis was performed and the chemical composition, hardness and the metal-ceramic bond strength were assessed. In addition, EDS analysis (mapping) was undertaken. Hardness and bond strength results were also statistically analysed. In spite of the fact that recasting brought about small changes in hardness and chemical composition (C, Cr and Mo), these effects were found to not affect their functional properties in the oral cavity. Still, significant differences between new alloy and the recasted groups (p < 0.05) were demonstrated in the course of statistical analysis of Vickers hardness test (for α = 0.05). All analysed research groups have a similar average adhesion at 48.51÷49.24 MPa (p > 0.05). The recasting procedure described in the paper can be done safely in dentistry. If previously casted material is used, it should be mixed with new material. The use of the material prepared in this way can lower the costs of NiCrMo castings.

With the rapid development of the road transport industry, trucks with semi-trailers have become the main means of transporting goods by road. High quality, durability and reliability of the construction are the main requirements for the production of trailers. Trailer and semi-trailer axles are one of the main and most important components of a truck. Due to the fact that semi-trailer axles are subjected to additional static and dynamic loads during operation, their proper construction is extremely important, therefore they should be carefully designed and tested. The durability of the suspension components refers to the duration of the onset of fatigue. This article presents an analysis of damage to the rear axle of the semi-trailer using macroscopic observations of the damage site and dynamic FEA of stress distribution in the axle material. In order to identify the probable cause of the damage, eight cases of loading the semi-trailer axle were considered. Analytical solutions have shown that in various cases the yield point is exceeded and the strength limit of the modeled semi-trailer axle is reached. The risk of damage to the vehicle’s suspension system components increases on poor roads (bumps and winding road sections).