Solid State Phenomena Vols. 147-149

Abstract: This study has focused on the chip-breaker design and experimental cutting of Inconel 718with the designed chip breaker. The process of chip breakage for Inconel 718 with respect to cutting speed, depth of cut and feed rate then chips and machined surfaces were analyzed from the experimental results. For this purpose, the nickel-base super alloy, Inconel 718was machined with a two layers PVD coated (TiAlN-TiN) carbide insert at feed rates of 0.10, 0.15, 0.20, 0.30 mm/rev, 0.5, 1, 1.5, 2 mm with depth of cuts, and 30, 45, 60, 75m/min cutting speeds using developed dynamic chip breaker with Negative tool holders in dry cutting conditions. Chip pictures and surface roughness (Ra) were recorded. Chip breakability during machining of the Inconel 718 depends on DC motor speed and chip breaker position on the cutting tool. The experimental results show that the designed chip breaker can break long chips at any cutting condition and acceptable surface finish can be achieved. In addition to this, according to cutting conditions, the usage of dynamic chip breaker on the surface of cutting insert is measured between 1% and 40% cooling effects using negative tool holder.

Abstract: In this paper there is presented the structure and proprieties of the modeling cast magnesium alloys as cast state and after heat treatment, depending on the cooling medium (furnace, water, air), with different chemical composition. The improvement of the manufacturing technique and chemical composition as well as of heat treatment and cooling methods leads to the development of a material designing process for the optimal physical and mechanical properties of a new developed alloy. In the analysed alloys a structure of solid solution and fragile phase  (Mg17Al12) occurred mainly on grain borders as well as eutectic and AlMnFe, Mg2Si phase. The investigation is carried out to testy the influence of the chemical composition and precipitation processes on the structure and mechanical properties of the magnesium cast alloys with different chemical composition in its as cast alloys and after heat treatment.

Abstract: The method of rhenium powder fabrication was presented in the paper. The powder was received by reduction of ammonium perrhenate. Rhenium was added to W+Ni+Fe powder mixture, then pressed (in the isostatic press), and next sintered in a vacuum furnace. Sinters containing rhenium are more fine-grained as compared to WNiFe alloys. Their average grain diameters are 11,7 µm and 25,6 µm respectively. Sinters with addition of rhenium are charac-terized by higher hardness, higher tensile and yield stress but lower density and elongation as com-pared to classical heavy alloys.

Abstract: The surface of an endosseous implant has fundamental importance in forming mechanical and chemical connection with osseous tissue. One of the methods of enlarging area is using technology of powder metallurgy. The paper presents research regarding osteointegration of porous materials for implants made for Co-Cr-Mo and titanium with Bioglass type-S2. The research was made on the castrated goats averaging one year of age, from this oneself herds. Bone growth process on surfaces of implants made with additional bioglass was significantly intense. The amount of osseous tissue and the number of connection points are significantly increased. On surfaces of titanium implants few areas of stochastic callus formation were observed. In that case areas of preferential bone integration have uneven surface due to technological process. A significant difference appears in osseous tissue growth morphology on implant surface. In porous implants bone grows around the pores of an implant. The obtained results showed that porosity influences callus growth intensity beneficially on the implant structure. Use of bioglass increases bone growth intensity on implant surface.

Abstract: Surface engineering is considered a very prospective method of improving functional properties of implant alloys. Many publications reported the excellent influence of TiN coating on wear resistance as well as corrosion properties of titanium alloys. However, some authors pointed the danger of delamination of thin coating during exploitation. The aim of presented work was research of effect of TiN coating obtained by the RF-PCVD method on tribological and corrosion properties of Ti6Al4V alloy. Investigations performed by the simulator of hip joint friction as well as corrosion tests carried out at various temperatures showed adverse influence of TiN coating on wear and corrosion resistance. Analysis of presented date demonstrate that results strongly depend on test conditions.

Abstract: The paper presents investigation results of the rheological and some physico-chemical properties of mixed and submandibular/sublingual saliva (both unstimulated). Samples were collected in accordance with a predetermined methodology in order to eliminate the influence of such factors as, for example, time elapsed since the last meal. The initial analysis of human saliva showed a considerable divergence of the studied physico-chemical and rheological parameters. It was found that the submandibular/sublingual saliva constitutes a better diagnostic basis than the mixed saliva.

Abstract: The paper presents problems involving the assessment of durability and reliability of dental prosthetics elements. It describes the most common defects of such elements, with special focus on the prosthetic bridges. A lot of attention was paid to the complexity and extent of the problem and the structure of testers for investigating such elements. The analysis of literature is followed by the author’s own design of specialist research system for complex analysis of dental prosthetics elements.

Abstract: In the paper own prepared materials with addition fluorine sources were evaluated. The aim of the study was to assess the quality and quantity of fluoride source on fluoride ions release from composite materials. Antibacterial activity of analyzed materials in relation to four bacteria was investigated. Fluoride ions release was measured by direct potentiometry method with fluoride ion selective electrode. The measurements were carried out after 1, 4, 7, 14, 30, 60 days of storage in buffer at pH 6.8. The antibacterial activity of the materials was evaluated against standard bacterial strains using the agar diffusion test. Tests show that the highest level of fluoride ions emission was observed for composite with fluoridated glass (material A) on the seventh day of the study. Similar fluoride ions amount was released from material consisted of fluoridated glass and ytterbium fluoride (material C), but not until on the thirtieth day of the study. After 24 hours of composite bonding there was inhibition of bacterial growth by composite C, whereas composite A did not show similar activity. On the eighth day after polymerization, both materials were significantly more active towards two bacteria.

Abstract: This work presents results of research of fluoride release, microhardness and surface roughness and wear of the Tetric EvoCeram material. Wear tests were carried out by means of special tribotester for tooth analysis and by pin-on-disc tribometer. The wear of composite material and counterface (human enamel) were measured. Finally, investigations showed that fluoride ions from commerce material were slightly released. However, the amount of fluoride ions release was depended on pH and temperature of agent solution. Fluorine emission from composite material changed its surface roughness and microhardness. The using method of wear process influenced on friction coefficient value. During friction process the wear layer on composite surface was formed.

Abstract: The paper presents the effect of dispersion phase of Al2O3 on selected potential properties of composite coatings on the nickel base. Coatings of Ni-Al-Al2O3 were applied on the steel specimens using the subsonic process of flame spraying. The specimens were then subjected to both cold and hot plastic working by rolling and also cold pressing by the hydraulic press. Plastic working is an alternative to machining, as the method of finishing of coats applied by flame spraying. The paper presents the findings of the research into the possibility of using plastic working (hot and cold rolling and pressing) to obtain the selected properties of the flame sprayed Ni-Al alloy coatings and Ni-Al-Al2O3 composite coatings. The alloy coatings had a single-phase structure, namely boundary solution α , of the maximum 10% aluminium solubility in the crystal lattice of nickel, whereas in the composite coatings the volume content of non-metallic material Al2O3 was: 0, 15, and 30 %.