Barbara Surowska

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...

The influence of fibre orientation in aluminium–carbon laminates on low-velocity impact resistance

The objective of this study was to assess the influence of fibre orientation in hybrid fibre metal laminates based on aluminium and carbon fibres on the impact of low-velocity impact. The analysis was conducted on the basis of fibre metal laminate impact resistance criteria, including impact force, energy absorption, bending stiffness, damage area and failure. To assess the resistance of various aluminium–carbon laminates, qualitative and quantitative evaluation criteria were employed, including the shape of the force–time curve, characteristic impact forces, energy absorption, bending stiffness, damage area and external failure analysis. Among others, authors concluded that no explicit influence of the composite layer fibre orientation on the shape and value of characteristic forces was observed. It was found that the fibre orientation and the changing number of interfaces of low durability show no explicit influence on the size and shape of delaminations.

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.

Qualitative analysis of the margins of restorations made with different filling resins

Purpose: In this study the comparative results obtained from examinations of two different restorative composites with different cavities filling method are presented. Micro‐CT was used for the evaluation of the marginal integrity and quality of composite fillings in connection with microstructural investigations made by both optical and scanning electron microscopy.

Study of low-cycle fatigue of glass-hybrid laminates

Purpose The purpose of the article is to present the results of research in the scope of fibre metal laminates reinforced with glass fibres in low-cycle fatigue conditions in the range of limited number of cycles. Design/methodology/approach The tests have been carried out on open hole rectangular specimens loaded in tension-tension at high load range of 80 and 85% of maximum force determined in static test, correspondingly. The number of cycles for destruction has been determined experimentally. Findings By means of microscopic observations, it was possible to determine the moment of cracks initiation and their growth rate. Furthermore, it was possible to identify the impact of reinforcing fibres orientation in composite layer, material creating the metal layers, on fatigue life and on nature of cracks propagation. Practical implications This work validates the possibility of increasing the resistance of metal-fiber laminates for low-cycle fatigue by modifying the structure of the laminate. Originality/v...