Jarosław Bieniaś

The influence of SiO2 and SiO2–TiO2 intermediate coatings on bond strength of titanium and Ti6Al4V alloy to dental porcelain

OBJECTIVES The purpose of this study was to evaluate the bond strength of commercially pure CPTi and Ti6Al4V alloy with SiO2 and SiO2-TiO2 intermediate coatings to Triceram low-fusing dental porcelain. METHODS The multilayered systems were characterized from the standpoint of microstructure analysis (SEM), the mode of failure, the nature of bonding and the influence of intermediate coatings on the improvement of bond strength. The SiO2 and SiO2-TiO2 intermediate coatings were applied on the substrate materials by the sol-gel dipping technique. The metal-ceramic bond strength was investigated according to ISO 9693 standards using the three-point flexure bond test. RESULTS Statistically significant higher bond strength of the metal-porcelain for Ti6A14V alloy (28.24 MPa), Ti6Al4V/SiO2 (32.17 MPa) and Ti6Al4V/SiO2-TiO2 (36.09 MPa) was noted in comparison to CPTi (23.04 MPa), CPTi/SiO2 (27.98 MPa) and CPTi/SiO2-TiO2 (28.84 MPa), respectively. The nature of metal-intermediate coating-porcelain bonding was both mechanical and chemical. The failure in all systems was cohesive and adhesive, mainly adhesive. SIGNIFICANCE The application of SiO2 and SiO2-TiO2 intermediate coatings, produced by the sol-gel method, to both CPTi and Ti6Al4V alloy significantly improves the bond strength of metal-porcelain systems in comparison to the metal substrate only after sandblasting, and may have clinical use.

Interface analysis of fiber metal laminates

Fiber metal laminates (FMLs) are the hybrid laminates consisting of alternating thin layers of metal sheets and fiber-reinforced composite material. Interface between metal and polymer layer plays a significant role. FMLs have both low density and high relative strength, and other good properties as high damage tolerance: fatigue and impact characteristics, corrosion, and fire resistance. In present work, the microstructure of the aluminum-epoxy/glass and aluminum-epoxy/carbon composites is characterized. The interface between metal and polymer composites with surface treatment and without surface treatment at different pressures was examined. It was observed that pretreatment of the aluminum has a significant effect on the zone between metal and polymer composite. In the interface, there is a direct contact between anodizing layer and resin without fibers, the same for epoxy/glass and epoxy/carbon laminates. The low pressure in autoclave process has a detrimental effect on the structure. It is responsible for the formation of the porosity and delamination in polymer layer and interface between aluminum and polymer composites. Untreated surface of aluminum sheet is characterized by too low adhesion to epoxy composite, especially with carbon reinforcement.

The impact behavior of aluminum hybrid laminates

Purpose – The purpose of this study was to carry out the analysis of impact resistance for aluminum hybrid laminates and polymer matrix composites reinforced with glass and carbon fibers. Damage modes and damages process under varied impact energies are also presented and discussed. Design/methodology/approach – The subject of examination were fiber metal laminates – FMLs (Al/CFRP and Al/GFRP). The samples were subjected to low-velocity impact by using a drop-weight impact tester. The specimens after impact were examined using non-destructive and destructive inspection techniques. Findings – The hybrid laminates are characterized by higher resistance to impact in comparison to the conventional laminates. The delaminations between composite layers as well as the delaminations on metal/composite interface and lateral cracks are the prevailing type of destruction mechanisms. No significant relationships between metal volume friction coefficient vs response to the impact were recorded for the hybrid laminates...

Experimental investigation on the influence of fibers orientation on the failure of carbon hybrid laminates

Purpose – The purpose of this paper is to present microstructural and fractographic analysis of damage in aluminum (2024T3)/carbon-fiber reinforced laminates (AlC) after static tensile test. The influence of fiber orientation on the failure was studied and discussed. Design/methodology/approach – The subject of examination was AlC. The fiber–metal laminates (FMLs) were manufactured by stacking alternating layers of 2024-T3 aluminum alloy (0.3 mm per sheets) and carbon/epoxy composites made of unidirectional prepreg tape HexPly system (Hexcel, USA) in [0], [± 45] and [0/90]S configuration. The fractographic analysis was carried out after static tensile test on the damage area of the specimens. The mechanical tests have been performed in accordance to ASTM D3039. The microstructural and fractographic analysis of FMLs were studied using optical (Nikon SMZ1500, Japan) and scanning electron microscope (Zeiss Ultra Plus, Germany). Findings – FMLs based on aluminum and carbon/epoxy composite are characterized by...

Numerical/phenomenological model for fatigue life prediction of hybrid laminates

In this article, the fatigue stress-cycle (S-N) curves of carbon fiber reinforced polymer (CFRP) and glass fiber reinforced polymer (GFRP) were investigated. Experimental fatigue tests were performed on unidirectional specimens and the S-N curves for GFRP and CFRP materials were determined. Obtained S-N curves were next described by phenomenological model (PM) based on mathematical function containing convexity and concavity ranges of stress-cycle curve. Based on the PM and numerical static analyses performed in ABAQUS/Standard on hybrid glass-carbon fiber reinforced polymer, the fatigue S-N curve was predicted for this material. Numerical/phenomenological model predictions were validated by experimental tests, where good agreement was obtained in the field of static tensile strength, shape of S-N curve and infinite fatigue life.

Structure and chemistry of fiber metal laminates

Fiber metal laminates (FMLs) are a modern group of hybrid composites consisting of metal sheets and layers of polymer composite reinforced with fiber. Desirable properties are being get throuwegh the selection of components and the configuration of layers. Nowadays, aluminum/glass fiber epoxy composite laminates type glass reinforced are most popular, but other metallic and fiber composite materials as components are widely examined. The adhesion of these components is achieved in manufacturing process during curing in autoclave or in vacuum bag using out-of-autoclave method. The metal layers are specially pretreated before the process of bonding with fibers/epoxy prepreg. A pretreatment is essential to promote one or several of the adhesion mechanisms (i.e., mechanical interlocking, physisorption, chemisorption) both improving the strength of the adhesive joint. The quality of FML depends on macrostructure and microstructure of composite—voids presence and their size, fiber distribution, and cohesion of plies; microstructure, topography, and the physical and chemical properties of metal surface; microstructure of interface—especially presence of delamination. Therefore, the macro- and microstructure characterization is very important as the first step for predicting the properties of FMLs.

Properties and characterization of fiber metal laminates

Abstract Fiber metal laminates are hybrid composites consisting of alternating thin layers of metal sheets and fiber-reinforced composites for advanced aerospace structural applications. FML possess superior properties of both metals and fibrous composite materials. Fiber metal laminates are characterized by low density, excellent impact resistance, high strength-static and fatigue properties, corrosion, and fire resistance. Specific fiber metal laminates are determined by the type of metal alloy, fiber/resin system, layer thickness, number of layers in the laminate, stacking sequence, and fiber orientations. The chapter presents mechanical and environmental properties and characterization of various laminates. Applications and future trends in FML are also discussed.

Damage Detection and Size Quantification of FML with the Use of NDE

Abstract Composite materials have been developed in recent years. A new generation of structural composite materials for advanced aircraft is Fibre Metal Laminates (FML). They are hybrid composites consisting of alternating thin layers of metal sheets and fiber-reinforced composite material. FMLs have both low weight and good mechanical properties (high damage tolerance: fatigue and impact characteristics, corrosion and fire resistance). Quality control of materials and structures in aircraft is an important issue, also for Fibre Metal Laminates. For FML parts, a 100% non-destructive inspection for internal quality during the manufacturing process is required. In the case of FML composites, the most relevant defects that should be detected by non-destructive testing are porosity and delaminations. In this paper, a number of different non-destructive methods for the inspection of Fibre Metal Laminates were studied. The possibility of quality control of manufactured FML laminates - detection of defects as well as the procedures and processes are presented and discussed

THE TRIBOLOGICAL CHARACTERISTICSOF Al-Si/GRAPHITE COMPOSITE

The paper presents the results of tribological research on AlSi12CuNiMg/5.7 wt.% Gr aluminium composite material (containing graphite particles in the amount of 5.7% wt.%) and on its matrix. This composite is used as high-tech construction material in the automotive industry, particularly for pistons, cylinder liners, and slide bearings. The tribological properties of these materials can be significantly changed as a result of the introduction of graphite particles. Therefore, wear tests have been carried out using the ball-on-disc tribometer. Microstructure and wear resistance of the matrix and composite alloy have been subjected to comparative analysis. It was demonstrated that the composite reinforced with graphite is characterized by a lower friction coefficient and lower wear in comparison to the matrix. Słowa kluczowe: aluminiowe materiały kompozytowe, grafit, tarcie ślizgowe, testy zużycia. Streszczenie: Artykuł przedstawia wyniki badań tribologicznych aluminiowego materiału kompozytowego AlSi12CuNiMg/5.7 wt.% Gr (zawierającego cząsteczki grafitu w ilości 5,7% wag.) i jego osnowy. Kompozyt ten znajduje zastosowanie jako nowoczesny materiał konstrukcyjny w przemyśle motoryzacyjnym, szczególnie na tłoki, tuleje cylindrowe i łożyska ślizgowe. Wprowadzenie cząstek grafitu znacząco może zmieniać właściwości tribologiczne tych materiałów. W tym celu wykonano testy zużycia na tribometrze typu kula-tarcza. Mikrostruktura i odporność na zużycie stopu osnowy i kompozytu zostały poddane analizie porównawczej. Wykazano, że kompozyt zbrojony grafitem charakteryzuje się mniejszym współczynnikiem tarcia i mniejszym zużyciem w porównaniu z osnową. * Lublin University of Technology, Faculty of Mechanical Engineering, Department of Materials Engineering, 36 Nadbystrzycka Street, 20-618 Lublin, Poland, e-mails: m.walczak@pollub.pl, j.bienias@pollub.pl. ** Wrocław University of Technology, Faculty of Mechanical Engineering, Institute of Production Engineering and Automation, 5 łukasiewicza Street, 50-371 Wrocław, Poland, e-mail: maciej.zwierzchowski@pwr.wroc.pl *** University of Life Sciences in Lublin, Faculty of Production Engineering, Department of Transporting and Agricultural Machinery, 28 Głęboka Street, 20-612 Lublin, Poland, e-mail: jacek.caban@up.lublin.pl INTRODUCTION Al-Si cast alloys are very popular in the transport industry due to their numerous attractive features, e.g., high strength to low specific gravity ratio, the low value of thermal expansion, excellent castability, and corrosion resistance [L. 1]. Al-Si eutectic alloys (i.e. AlSi12CuNiMg) are mainly used in the automotive industry for the manufacturing of pistons, cylinder liners, connecting rods, and engine blocks [L. 2, 3]. Recently Aluminium Matrix Composites (AlMC) reinforced with fine ceramic graphite particles, fly ash, SiC, and Al2o3 particles are increasingly gaining in importance in the scope of scientific research works and in implementation activities [L. 4–6]. From among the wide spectrum of metal composite materials, the materials based on the system consisting of aluminium alloy – graphite particles (Al/Gr) deserve a special mention. Excellent physicochemical and operational properties are achieved thanks to the presence of dispersed graphite particles in aluminium matrix [L. 7]. Moreover, the presence of solid, soft, and lubricating graphite particles in aluminium matrix leads to the significant improvement of anti-seizing properties and to better vibration damping [L. 7, 8]. The anti98 ISSN 0208-7774 T R I B O L O G I A 1/2017 seizing properties of Al/Gr composites are particularly important in the case of cold engine starting or the lack of proper lubrication. Casted pistons of compression-ignition (Diesel) engines made of Al-Si/Gr composites reduce the value of specific fuel consumption by 3% and the value of engine power losses caused by friction by 9% in comparison to applied conventional aluminium alloys of cast iron [L. 9]. It is possible due to the presence of lubricating graphite layer, high vibration damping capability, and the low value of thermal expansion coefficient. The high vibration damping capability of Al-Si/Gr pistons eliminates the piston slap and piston ring clearance as well as maintains a continuous hydrodynamic oil coating, reducing the friction between piston ring and sleeve surface as well as reducing the wearing of piston rings [L. 10, 11]. Aluminium is characterized by significant reactivity and by the local increase of mating elements temperature in the course of sliding resulting in surface oxidation [L. 10, 12]. Investigations [L. 13] on the impact of Si content on wear in aluminium casting alloys indicated that abrasion wear occurs at a Si content of 12%. The authors emphasize that mainly two abrasive wear mechanisms are present in such case: (1) ploughing action in the case of alloys subjected to heat treatment and (2) the combination of ploughing action and cutting in the case of alloys not subjected to heat treatment. Furthermore, they show that nucleation of Al alloy cracks takes place mainly on the Al/Si contact surface due to the high stress concentration on the interface between Si particles and Al matrix. Needle-shaped eutectoid Si will easily lead to the nucleation and propagation of cracks. This state is eliminated by the spheroidization of eutectic silicon as a result of heat treatment. In the course of the analysis of abrasive wear in eutectic Al-Si alloys, Mahato et al. [L. 14] observed Si decohesion from the matrix resulting in the occurrence of regional cracks. In all probability, this process is facilitated by high velocities of deformation in subsurface regions, and it causes the accumulation of dislocations on Si borders. Furthermore, the increasing occurrence of brittle oxides is observed in the region of micro-cracks occurrence due to increased oxygen diffusion. In the opinion of Omrani et al. [L. 10], graphite particles reduce the value of shear stress and plastic deformations in sub-surface area performing the role grease between the both slipping surfaces. Rajaram et al. [L. 15] indicate that wear progress in Al-Si/Gr composites takes place through the creation of sub-surface cracks, which locate at the previous location of separated Si particles in matrix alloy due to high shear stress. The wear is determined by occurring delaminations and the coalescence of these cracks. Then the wear process is carried out in the form of the removal of successive layers of material as a result of the delamination of sub-surface layers. The application of aluminium alloy graphite particles in combustion engines elements, e.g., cylinder liners, significantly reduces their wear, improves the efficiency, increases the engine power, and reduces operation costs. The reduction of losses caused by friction between the piston and cylinder liner can significantly contribute to the increase of mechanical efficiency [L. 11]. The cylinder liners used by Honda Corporation (staple fibre 12% Al2o3, 9% graphite) are integrated with the cylinder block. The thickness of friction layer has been reduced to 2/3 in comparison to previously used aluminium alloy and the previous mass was maintained. However, the mass has been reduced by 50% in comparison to cast iron inserts. Cooling effectiveness has been improved in a significant manner [L. 16]. The bearings characterized by lower weight, selflubricating, and generating lower production costs in comparison to currently manufactured bearings, e.g., made of copper, lead, tin, and cadmium alloys can prove to be the most promising application of casted Al/Gr composites [L. 8]. The friction joint and particularly the type of directly contacting materials are important in tribological processes. The knowledge of tribological characteristics and wearing mechanisms is essential in the course of designing, selection of materials and in the course of the selection of machine parts production technology. Therefore, the purpose of the research was to determine the impact of reinforcing layer (in the amount of 5.7 wt.% graphite) on wearing in dry sliding condition in regards to matrix alloy AlSi12CuNiMg. MATERIAL AND METHODS AlSi12CuNiMg casting aluminium alloy reinforced with fine graphite particles in the amount 5.7 wt.% has been used in tests. AlSi12CuNiMg/5.7 wt.% Gr composite was manufactured in the Foundry Research Institute in Cracow in the gravity casting process. Graphite particles coated with nickel (NOVAMET, 60 wt.% Ni) with average dimensions of 75–120 μm were introduced into liquid matrix alloy through mechanical mixing. Neareutectic AlSi12CuNiMg alloy constituting the matrix of composite to be tested was used as a comparative material. The tests were performed on raw specimens (not subjected to heat treatment). The chemical composition of AlSi12CuNiMg alloy is presented in Table 1. Disc shaped specimens with a diameter of 25 mm and thickness of 6 mm were used for tribological tests. Three (n=3) specimens from each test material group were used for wear test. The specimens were subjected to grinding on water abrasive papers with grains size of 220, 600 and 1200, sequentially. Then the specimens 99 ISSN 0208-7774 T R I B O L O G I A 1/2017 were subjected to mechanical polishing by means of a suspension of diamond particles (3 μm), a suspension of oxides particles (0.05 μm), washed with acetone, and dried in a warm air stream thereafter. The roughness Ra of the materials subjected to polishing reached level Ra≈0.05 μm. Surface preparation of the samples was dictated by the desire to obtain accurate results when determining the wear factor (according to ASTM G40) on the basis of measurements of profilometric wear volume. Wear tests were completed on a ball-on-disc tribometer manufactured by CSM Instruments. Dry sliding wear tests were conducted according to the ASTM G99-95c [L. 18] and DIN 50 324 standard [L. 19]. Balls with a diameter of 6 mm made of 100Cr6 steel with

Interrelationships Between Morphometric, Densitometric, and Mechanical Properties of Teeth in 5-Month-Old Polish Merino Sheep

Interrelationships between morphological, densitometric, and mechanical properties of deciduous mandibular teeth (incisors, canine, second premolar) were investigated. To perform morphometric, densitometric, and mechanical analyses, teeth were obtained from 5-month-old sheep. Measurements of mean volumetric tooth mineral density and total tooth volume were performed using quantitative computed tomography. Microcomputed tomography was used to measure total enamel volume, volumetric enamel mineral density, total dentin volume, and volumetric dentin mineral density. Maximum elastic strength and ultimate force of teeth were determined using 3-point bending and compression tests. Pearson correlation coefficients were determined between all investigated variables. Mutual dependence was observed between morphological and mechanical properties of the investigated teeth. The highest number of positive correlations of the investigated parameters was stated in first incisor indicating its superior predictive value of tooth quality and masticatory organ function in sheep. Positive correlations of the volumetric dentin mineral density in second premolar with final body weight may indicate predictive value of this parameter in relation with growth rate in sheep. Evaluation of deciduous tooth properties may prove helpful for breeding selection and further reproduction of sheep possessing favorable traits of teeth and better masticatory organ function, leading to improved performance and economic efficiency of the flock.