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This study investigates the utilization of basalt in manufacturing machinable glass ceramics. As the fluorine and potassium phases, MgF2 and K2O added into basalt are responsible for the machinability of glass ceramics. Three different compositions containing 80%, 85%, and 90% basalt, with K2O and MgF2 as the remainder, were mixed and melted in an alumina crucible at 1500 °C. Glass samples were obtained by casting the melt into a graphite mould. Glass ceramics were prepared through subsequent crystallization heat treatment of the obtained glass. Compositional and mechanical characterizations were carried out via XRD-SEM and hardness/fracture toughness and machinability tests respectively. The effect of change in the obtained phases with basalt composition on the machinability of glass ceramics was investigated. Furthermore, crystallization kinetics of the glasses were investigated by differential thermal analysis (DTA) using the Kissinger kinetic model with several different heating rates. This study reports that basalt can be utilized in the production of machinable glass ceramics only if the basalt ratio is justified. The results showed that good machining performance was observed in low-basalt content conditions (B80), When the basalt content increased (B85 and B90), the machining capability decreased markedly. Furthermore, the crystallization activation energies decreased with increase in basalt content.

Solid oxide fuel cell (SOFC) is a very efficient and clean source of energy. The glass and glass-ceramics are the most suitable and compatible sealing materials for SOFC. The crystallization kinetics of glass sealants is an essential parameter to check the suitability of glass as a sealant. In this study, the crystallization behavior of a novel sealing glass developed from the volcanic rock basalt suitable as an SOFC sealant is investigated via differential thermal analysis using the Kissinger kinetic model with several different heating rates. Development of crystalline phases on thermal treatments of the glass at various temperatures has been followed by X-ray diffraction. Augite and diopside are the primary crystalline phases in crystallized glass-ceramic seals. The results show that the basalt base glass-ceramic sealant material exhibited promising properties to use for SOFC.

In this study, the effect of impact angle of the particles on solid particle erosive wear properties of basalt base glass-ceramics used for industrial applications was investigated. Commercial basalt glass-ceramic materials size of 2 0 x 2 0 x 3 cm was sectioned to the size of 5 x 5 x 1 : 2 cm. The experimental procedure was performed by using erosive wear test device with nozzle diameter of 0.78 cm. Na feldspar size of 300 mu m was used as erosive media. The samples were fixed 2 cm distance from the nozzle, Na feldspar particles were sprayed by using 1.5, 3, 4 bar pressure for 20 s. The tests were repeated with 30 degrees + 45 degrees + 60 degrees + 75 degrees + 90 degrees impact angles. The erosive wear rates were measured and the effect of particle impact angle on wear properties was determined.

Glass-ceramics were produced by sintering method from industrial waste materials such as fly ash, blast furnace slag and boron waste. The sintering behavior and machinability of glass-ceramic compositions were investigated. Additives were added to waste materials for enhancement of machinability and sintering properties. All starting materials were mixed by ball milling for 2 h using alumina media. The mixed and milled powders were sieved to grain sizes smaller than 75 mu m and pressed at 100 MPa. The pressed samples were sintered at 900 degrees C, 1000 degrees C and 1100 degrees C for 1 h in an electric furnace using a heating rate of 5 degrees C/min. Some characterization tests such as X-ray diffraction (XRD), scanning electron microscopy (SEM) and machinability tests were performed on sintered samples. The results indicated that all samples exhibit good sintering and machinability properties.

6th International Congress and Exhibition on Advances in Applied Physics and Materials Science (APMAS) -- JUN 01-03, 2016 -- Istanbul, TURKEY, WOS: 000396118600048, In this study, machinable glass-ceramics were produced from vermiculite and K2CO3, SiO2, Al2O3 and MgF2 as additives by melting process. The starting materials were mixed together and milled in a mill with alumina ball for 2 h. The mixed powders were melted by aluminum crucible at 1500 degrees C. The melted glass was cast into graphite mold, and then it was exposed to crystallization heat treatment for glass-ceramic transformation. The glass-ceramic samples were characterized with X-ray diffraction analysis, scanning electron microscopy, mechanical tests such as hardness, fracture toughness and machinability test. The results indicate that machinability properties can be obtained from vermiculite based glass-ceramic with some additives.

The crystallisation kinetics of the conversion of a glass coating layer made from a mixture of natural basalt volcanic rock and SiC into glass-ceramic have been investigated. The process depends on the crystallisation temperature, time and amount of the SiC added. Coating powders were prepared from pure basalt and from basalt containing 10-50 wt% SiC. The powders were coated by an atmospheric plasma spray technique on the pre-coated AISI 1040 steel substrate with Ni-Al. The coating layer was vitrified by sudden cooling. The amorphous structure of the coatings was verified by X-ray diffraction (XRD) analysis. To obtain glass-ceramic, coatings were subjected to crystallisation heat treatment in an argon atmosphere. Crystallisation heat treatment temperatures of 800 degrees C, 900 degrees C and 1000 degrees C were chosen by using DTA. After the heat treatment process, augite, ferrian-diopsite, diopside, albite, andesine, and moissonite phases formed in the coating layer and were verified by XRD analysis. The crystallisation activation energies were determined to be between 323.4 kJ/mol and 253.2 kJ/mol, depending on SiC addition. The crystallisation activation energies decreased with increasing amounts of SiC addition. The Avrami parameters of the crystallisation process varied between 1.60 and 3.33, which indicates that internal crystallisation dominated for all of the compositions. (C) 2012 Elsevier Ltd and Techna Group S.r.l. All rights reserved. https://doi.org/10.1016/j.ceramint.2012.05.037

In the present study, the effect of SiC addition on properties of basalt base glass-ceramic coating was investigated. SiC reinforced glass-ceramic coating was realized by atmospheric air plasma spray coating technique on AISI 1040 steel pre-coated with Ni + 5 wt.%Al bond coat. Composite powder mixture consisted of 10%, 20% and 30% SiC by weight were used for coating treatment. Controlled heat treatment for crystallization was realized on pre-coated samples in argon atmosphere at 800 degrees C, 900 degrees C and 1000 degrees C which determined by differential thermal analysis for 1-4 h in order to obtain to the glass-ceramic structure. Microstructural examination showed that the coating performed by plasma spray coating treatment and crystallized was crack free, homogeneous in macro-scale and good bonded. The hardness of the coated samples changed between 666 +/- 27 and 873 +/- 32 HV0.01 depending on SiC addition and crystallization temperature. The more the SiC addition and the higher the treatment temperature, the harder the basalt base SiC reinforced glass-ceramic coating became. X-ray diffraction analysis showed that the coatings include augeite [(CaFeMg)-SiO3], diopside [Ca(Mg0.15Fe0.85)(SiO3)(2)], albite [(Na,Ca)Al(Si,Al)(3)O-8], andesine [Na0.499Ca0.492(Al1.488Si2.506O8] and moissanite (SiC) phases. EDX analyses support the X-ray diffraction analysis. (c) 2010 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

The grain growth kinetics in the 0, 2 and 4 wt.% TiO2 added ZnO–6 wt.% Bi2O3 system was studied using the simplified phenomenological grain growth kinetics equation $$G^n = k \cdot t \cdot \exp ( - Q/R \cdot T)$$ together with the physical properties of the sintered samples. The grain growth exponent value (n) and the apparent activation energy for the ZnO–6 wt.% Bi2O3 system was 5 and 218 kJ/ mol, respectively. The addition of the TiO2 to the ZnO–6 wt.% Bi2O3 system inhibited the ZnO grain growth. At 2 and 4 wt.% TiO2 additions, the apparent activation energies were calculated as 467 and 346 kJ/ mol, respectively. The addition of TiO2 to the system inhibited the grain growth of ZnO ceramics.