J. W. Kaczmar

Technology and mechanical properties of ceramic preforms for composite materials

Abstract The production technology and properties of porous preforms for the reinforcing of composite materials are discussed in this paper. The preforms were produced by the mixing of alumina “Saffil” fibres with inorganic and organic binders followed by forming, drying and firing. Applying standard methods, the effect of porosity on the T c hardness, tensile strength and bending strength were investigated. The preforms produced showed good properties, making possible their infiltration by liquid metal alloys. Microscopic investigations revealed good joints between the fibres. Ceramic preforms of 75–90% porosity were produced, the technology making possible the production of preforms from different reinforcing fibres.

New biocomposites based on bioplastic flax fibers and biodegradable polymers

A new generation of entirely biodegradable and bioactive composites with polylactic acid (PLA) or poly‐ε‐caprolactone (PCL) as the matrix and bioplastic flax fibers as reinforcement were analyzed. Bioplastic fibers contain polyhydroxybutyrate and were obtained from transgenic flax. Biochemical analysis of fibers revealed presence of several antioxidative compounds of hydrophilic (phenolics) and hydrophobic [cannabidiol (CBD), lutein] nature, indicating their high antioxidant potential. The presence of CBD and lutein in flax fibers is reported for the first time. FTIR analysis showed intermolecular hydrogen bonds between the constituents in composite PLA+flax fibers which were not detected in PCL‐based composite. Mechanical analysis of prepared composites revealed improved stiffness and a decrease in tensile strength. The viability of human dermal fibroblasts on the surface of composites made of PLA and transgenic flax fibers was the same as for cells cultured without composites and only slightly lower (to 9%) for PCL‐based composites. The amount of platelets and Escherichia coli cells aggregated on the surface of the PLA based composites was significantly lower than for pure polymer. Thus, composites made of PLA and transgenic flax fibers seem to have bacteriostatic, platelet anti‐aggregated, and non‐cytotoxic effect.

Application of Polymer Based Composite Materials in Transportation

The purpose of this paper is to present the latest applications of fibre-reinforced polymer matrix composites described on exemplary applications. It contains the description of various examples, which were classified into the following categories: aerospace, automotive, marine, military and sport and leisure industry.

TEM Investigation of Interfaces Formed between SaffilTM Fibers and AA6061 and En Ac 44200 Aluminium Alloys

The metal matrix composites (MMC) were produced by force infiltration of preforms containing up to 10 vol % of Saffil fibers with AA6061 and EN AC 44200 aluminium alloys. The fibers were stabilized inside preform by dipping in liquid glass and heat treated at 800oC/2 hours. It allowed both to coat fibers with a thin layer of silica and bond fibers with amorphous silica bridges producing self supporting porous structure. The microstructure observations were performed using Tecnai FEG (200kV) transmission electron microscope. The performed investigations showed that infiltrating preform with AA6061 alloy with ~1 wt. % Mg caused reaction of silica with liquid metal substituting the former with porous amorphous Al2O3. A presence of MgO at the interfaces with aluminium matrix was noted. The infiltration with low magnesium EN AC 44200 (Mg <0.6 wt.%) alloy helped to produce composite with the silica bridges between fibers practically intact.

Local Strengthening of EN AC-44200 Al Alloy with Ceramic Fibers

The applied squeeze casting technique makes possible the local strengthening with ceramic fibers or ceramic particles of elements with Al-alloy matrices. In this paper the elaborated technology of manufacturing of porous ceramic preforms from Saffil fibers is shown and technology of squeeze casting elaborated at Wrocław University of Technology, Chair Foundry, Polymers and Automation described. There were applied the preforms characterized by porosities of 90% and 80%, what after squeeze casting with liquid EN AC - 44200 Al alloy produces the composite materials containing 10 vol. and 20 vol.% of fiber strengthening. The structural phenomena at the interface of strengthened alloy investigated with the optical and electron microscopy are discussed and the mechanical properties of manufactured composite materials are shown.