Colonization of polymeric dental prosthetic materials by yeast-like fungi and the association of these microorganisms with complications occurring during prosthetic treatment are important clinical problems. In previously presented research, submicron inorganic particles of silver sodium hydrogen zirconium phosphate (S-P) were introduced into poly(methyl methacrylate) (PMMA) denture base material which allowed for obtaining the antimicrobial effect during a 90 day experiment. The aim of the present study was to investigate the flexural strength, impact strength, hardness, wear resistance, sorption, and solubility during three months of storage in distilled water. With increasing S-P concentration after 2 days of conditioning in distilled water, reduced values of flexural strength (107-72 MPa), impact strength (18.4-5.5 MPa) as well as enhanced solubility (0.95-1.49 µg/mm 3 ) were registered, but they were at acceptable levels, and the sorption was stable. Favorable changes included increased hardness , flexural modulus (2.9-3.3 GPa), and decreased volume loss during wear test (2.9-0.2 mm 3 ). The percentage changes of the analyzed properties during the 90 days of storage in distilled water were similar for all materials.

Light metal alloys due to several unique properties such as low density and high corrosion resistance are increasingly used in various technical applications, where the automotive industry is one of the most important sectors. The automotive applications use mostly aluminum alloys, where the strength to density ratio of the material plays a crucial factor. Unfortunately, relatively low mechanical properties limit their applications for parts where a high surface hardness and wear resistance is expected. The classic heat treatment of aluminum alloys can only in some limited ranges improve the bulk material properties. Despite this, surface treatment with laser processing has developed significantly over the past 20 years. The laser beam treatment allows the introduction of a wide range of alloying elements to the surface layer of an aluminum alloy and thus, as a result of the precipitation of numerous intermetallic phases, significantly increases hardness, and abrasion resistance. The purpose of this work was to modify the aluminum surface layer using high-power fiber laser (HPFL). During this process, a mixture of titanium and iron powders (90/10 wt.%) was introduced onto the surface of the AlMg5 alloy. The microhardness tests carried out by the Vickers method and tribological tests showed a significant increase in mechanical properties in the entire volume of the obtained layer. Research on light and scanning microscopy revealed fragmentation of primary precipitates and the formation of numerous intermetallic phases rich in titanium and aluminum.Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Laser surface treatment is successfully applied to increase hardness as well as corrosion and wear resistance in light alloys such as aluminum or magnesium. The laser surface remelting also can be used to repair superficial cracks, voids or porosity caused by the mechanical impact, metallurgical process as well as the corrosive environment on the surface of the aluminum alloy. The purpose of this paper was to investigate the influence of a fiber laser surface treatment on the structure and properties of the EN AC AlMg5Si2Mn alloy. The goal of this investigation was to increase the hardness and improve tribological properties of the aluminum alloy surface as a result of the conducted laser surface treatment. During laser processing, the top surface of the aluminum alloy was enriched with Cr and Ni particles. The grain size of the applied particles was approximately about 60-130 m. The Cr-Ni powder has been introduced in the molten pool using vacuum feeder at a constant rate of 4.5 g/min. For surface remelting we used square laser beam at a size 3 × 3 mm and with the power of 3.0 kW. The linear laser scan rate of the beam was set at 0.5 m/min. Argon was used to protect the liquid metal alloy during surface treatment. Application of the laser treatment on aluminum alloy has enabled to obtain much harder as well as better wear resistant material compared to the untreated EN AC AlMg5Si2Mn.

Increasingly high expectations for modern engineering, make the constantly being sought-after new processes giving traditional materials new, better features. Nowadays, next to the classic heat treatments, advanced technologies are being used increasingly, leading to much better results than ever before. The most commonly used technologies that allow for obtaining new, enhanced properties of various metal alloys in the area of surface engineering include, among others laser surface treatment. The main objective of this paper was to analyze the influence of laser surface treatment on structural change and mechanical properties improvement of Al-Mg alloy by VC alloying. The remelted layer on the aluminium alloy surface was obtained using high power fiber laser "Ytterbium Laser System YLS-4000". The surface sample was remelted using a rectangular laser beam (2 x 4mm) with a power of 3 kW (1.53e+4w/cm2). Scanning speed of the laser beam was 0.8 cm/s (0.48 m/min). The remelting area has been protected by the use of technical argon blowing. During the process, sintered particles of vanadium carbide with an average size of about 50-100 μm was introduced into the liquid metal. Ceramic powder in the remelting volume was fed with a pressure feeder (constant rate of 5 g/min). As a substrate, the ENAC AlMg3 alloy has been used. During the laser treatment, a composite layer with much better mechanical properties was obtained comparing the base material. The average hardness of the layer was about 19 HV0.1higher than that of the base material. Chemical analysis, carried out with the EDS (energy dispersive spectroscopy) detector and transmission microscope revealed many undissolved powder particles used in the alloying process as well as those of Al8V5precipitated in the Al-Mg matrix.