The paper presents results of bend tests at elevated temperatures of aluminium alloy EN AC-44200 (AlSi12) based composite materials
reinforced with aluminium oxide particles. The examined materials were manufactured by squeeze casting. Preforms made of Al2O3
particles, with volumetric fraction 10, 20, 30 and 40 vol.% of particles joined with sodium silicate bridges were used as reinforcement. The
preforms were characterised by open porosity ensuring proper infiltration with the EN AC-44200 (AlSi12) liquid alloy. The largest
bending strength was found for the materials containing 40 vol.% of reinforcing ceramic particles, tested at ambient temperature. At
increased test temperature, bending strength Rg of composites decreased in average by 30 to 50 MPa per 100°C of temperature increase.
Temperature increase did not significantly affect cracking of the materials. Cracks propagated mainly along the interfaces particle/matrix,
with no effect of the particles falling-out from fracture surfaces. Direction of cracking can be affected by a small number of
agglomerations of particles or of non-reacted binder. In the composites, the particles strongly restrict plastic deformation of the alloy,
which leads to creation of brittle fractures. At elevated temperatures, however mainly at 200 and 300°C, larger numbers of broken,
fragmented particles was observed in the vicinity of cracks. Fragmentation of particles occurred mainly at tensioned side of the bended
specimens, in the materials with smaller fraction of Al2O3 reinforcement, i.e. 10 and 20 vol.%.
The paper presents results of compressive strength investigations of EN AC-44200 based aluminum alloy composite materials reinforced
with aluminum oxide particles at ambient and at temperatures of 100, 200 and 250C. They were manufactured by squeeze casting of the
porous preforms made of α-Al2O3 particles with liquid aluminum alloy EN AC-44200. The composite materials were reinforced with
preforms characterized by the porosities of 90, 80, 70 and 60 vol. %, thus the alumina content in the composite materials was 10, 20, 30
and 40 vol.%. The results of the compressive strength of manufactured materials were presented and basing on the microscopic
observations the effect of the volume content of strengthening alumina particles on the cracking mechanisms during compression at
indicated temperatures were shown and discussed. The highest compressive strength of 470 MPa at ambient temperature showed
composite materials strengthened with 40 vol.% of α-Al2O3 particles.
The paper presents the results of research of impact strength of aluminum alloy EN AC-44200 based composite materials reinforced with
alumina particles. The research was carried out applying the materials produced by the pressure infiltration method of ceramic preforms
made of Al2O3 particles of 3-6m with the liquid EN AC-44200 Al alloy. The research was aimed at determining the composite resistance
to dynamic loads, taking into account the volume of reinforcing particles (from 10 to 40% by volume) at an ambient of 23°C and at
elevated temperatures to a maximum of 300°C. The results of this study were referred to the unreinforced matrix EN AC-44200 and to its
hardness and tensile strength. Based on microscopic studies, an analysis and description of crack mechanics of the tested materials were
performed. Structural analysis of a fracture surface, material structures under the crack surfaces of the matrix and cracking of the
reinforcing particles were performed.
Development of open cellular metal foam technology based on investment casting applying the polyurethane pattern is discussed.
Technological process comprises preparing of the ceramic mold applying PUR foam as the pattern, firing of the mold, pouring of the
liquid Zn-Al alloy into the mold and washing out of the ceramic material from cellular casting. Critical parameters such as the temperature
of mold and poured metal, design of gating system affected by metalostatic pressure allowed to produce castings with cellular structure
characterized by the open porosity.
Metal cellular foams with the open porosity embedded in phase change material (PCM) enhance heat transfer and reduce time operations
in energy storage systems. Charging and discharging were performed at the laboratory accumulator by heating and cooling with flowing
water characterized by the temperatures of 97-100oC. Temperature measurements were collected from 7 different thermocouples located
in the accumulator. In relation to the tests with pure paraffin, embedding of the metal Zn-Al cellular foam in paraffin significantly
decreases temperature gradients and melting time of paraffin applied as PCM characterized by the low thermal conductivity. Similarly,
reduction of discharging time by this method improves the efficiency of thermal energy storage system applied in solar power plants or for
the systems of energy efficient buildings.
The aim of this work is the development of Cu-Al2O3 composites of copper Cu-ETP matrix composite materials reinforced by 20 and 30
vol.% Al2O3 particles and study of some chosen physical properties. Squeeze casting technique of porous compacts with liquid copper
was applied at the pressure of 110 MPa. Introduction of alumina particles into copper matrix affected on the significant increase of
hardness and in the case of Cu-30 vol. % of alumina particles to 128 HBW. Electrical resistivity was strongly affected by the ceramic
alumina particles and addition of 20 vol. % of particles caused diminishing of electrical conductivity to 20 S/m (34.5% IACS). Thermal
conductivity tests were performed applying two methods and it was ascertained that this parameter strongly depends on the ceramic
particles content, diminishing it to 100 Wm-1K-1 for the composite material containing 30 vol.% of ceramic particles comparing to 400
Wm-1K-1 for the unreinforced copper. Microstructural analysis was carried out using SEM microscopy and indicates that Al2O3 particles
are homogeneously distributed in the copper matrix. EDS analysis shows remains of silicon on the surface of ceramic particles after
binding agent used during preparation of ceramic preforms.
Investment casting combined with the additive manufacturing technology enables production of the thin-walled elements, that are geometrically complex, precise and can be easy commercialized. This paper presents design of aluminium alloy honeycombs, which are characterized with light structure, internal parallel oriented channels and suitable stiffness. Based on 3D printed pattern the mould was prepared from standard ceramic material subjected subsequently to appropriate heat treatment. Into created mould cavity with intricate and susceptible structure molten AC 44200 aluminium alloy was poured under low pressure. Properly designed gating system and selected process parameters enabled to limit the shrinkage voids, porosities and misruns. Compression examination performed in two directions showed different mechanisms of cell deformation. Characteristic plateau region of stress-strain curves allowed to determine absorbed energy per unit volume, which was 485 or 402 J/mm3 depending on load direction. Elaborated technology will be applied for the production of honeycomb based elements designated for energy absorption capability.