Presented paper contains description and interpretation of the results of selected physicochemical and structural properties of two types of composite sinters. They were constituted of a mixture of sintered microcrystalline corundum and bioglass CaO-P2O5-SiO2-Na2O system intended for scaffolds to cell culture of human chondrocytes. The composites contained a mixture of both above-mentioned components in the volumetric proportion of 50:50 (W5) and 30:70 (W7). They were obtained using powder metallurgy by free sintering in air atmosphere. Phase analysis of composites and verification of theoretical identification using X-ray diffraction were performed. The same phases were found in both cases (Al2O3 SiO2 CaAl2Si2O8, Ca3 (PO4)2, Ca2Al4O7 and NaAlSiO4). Microscopic tests of composite surfaces were performed and some differences were found. W5 sample was not completely covered with bioglass, whilst W7 sample was completely covered with bioglass with few fine pores. Tests of surface topography confirmed the presence of large and small pores. Composite surfaces immersed for 30 days in artificial blood plasma were tested and then electron microscopy analysis was performed. It was found that no significant changes occurred on the surface of the W5 composite, probably partial corrosion of the glass happened. Spherical forms characteristic of HA-hydroxyapatites were observed on the surface of sample W7. Human articular chondrocyte cells were seeded on both types of sinters and proliferation assay was performed. Results indicate that tested scaffolds support cellular attachment and proliferation of chondrocytes.
The influence of mechanochemical treatment of sintered submicrocrystalline corundum substrates on the structure of bioglass composites The influence of mechanochemical treatment of submicrocrystalline sintered corundum on the structure of bioglass composites containing α-Al 2 O 3 and CaO-SiO 2-P 2 O 5 glasses was examined in the context of the possibility to form hydroxyapatite after being immersed in the simulated body fluid solution. Measurements of specific surface area and size and X-ray analysis of submicrocrystalline sintered corundum were conducted. Bioglass composites were obtained by placing submicrocrystalline sintered corundum grains in the CaO-SiO 2-P 2 O 5 sol system, gelling and sintering at 800 °C. The specimens were examined under a scanning electron microscope before and after immersion in the simulated body fluid solution for 24 and 120 h. Using the VCS algorithm, calculations of thermodynamic stability of compounds occurring in these bioglass composites were carried out, verifying the X-ray analysis.
The paper presents the results of research into the influence of the process of grinding boron nitride dispersed cemented carbide (BNDCC) composite using diamond wheel with vitrified bond on the selected properties of this composite. Cutting tools of BNDCC composite were manufactured using several machining operations. At first stage, they were EDM (electrical discharge machining) wire cut from tablets and later on ground with diamond wheels (which removed the "white layer" produced by EDM cutting). Rake and flank faces of prepared cutting tools were examined by microscopic, topographic, and surface analytical techniques before and after grinding. The paper presents comparative results of BNDCC tools and tools made of H10S cemented carbide. Values of the grinding efficiency parameters, Q w , average material removal rate of grinding, Q′ w , average material removal rate per unit active grinding wheel for the two materials, were similar, indicating an insignificant effect of introduction of the harder BN phase into WCCo on these parameters. R a , surface roughness of flank face, was 0.040 μm for BNDCC composite and 0.51 μm for H10S after grinding, compared to 1.14 and 1.30 μm, respectively, before grinding. WC residual stress measurements in the flank faces of BNDCC tools were inconclusive; in the flank faces, the stresses were compressive, decreasing, e.g., from − 230 to − 1670 MPa after grinding. For the H10S tools, there was no comparable effect. The results also indicate that the vitrified bonded diamond abrasive wheel used is effective in grinding WCCo and BNDCC cutting tools.
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