Effect Of Feldspar Research Articles

Effect of feldspar and silica variation on the properties of dental porcelain

Dental porcelain was produced by mixing feldspar, silica, kaolin and bone ash by varying the contents of feldspar and silica. The processing steps include milling, sieving, pressing/shaping, drying, and sintering while the characterisation techniques were Hardness, Compressive strength, X-ray diffraction, Scanning electron microscopy and Fourier Transform Infrared (FTIR). The mixture was subjected to temperatures of 1100 and 1200 oC in a sintering furnace. The chemical composition was determined using X-ray fluorescence and they confirm that SiO2 and Al2O3 are the two major constituents in feldspar and kaolin while CaO is the major constituent in bone ash. For samples sintered at 1200oC, the X-ray diffraction showed that some glass phase possibly consisting of hedenbergite, ilmenite and silica were formed while crystalline phases namely microcline and sanidine were obtained for samples sintered at 1100°C. The morphology of the grains revealed that samples sintered at 1200oC had some hexagonal silica crystals while flakes of different sizes were obtained for samples sintered at 1100oC. Hardness values between 262 and 536 BHN, compressive modulus values ranging from 219 MPa to 324 MPa and linear shrinkage values between 6.34 and 7.6% were obtained. The batches of different compositions with ranges: quartz (silica) (15-25%), feldspar (70-80%), kaolin (Edda/Bauchi) (4%) and bone ash (1%) were fired at 1100, 1200oC, and the developed properties were tested. The sample with 70 wt.% of feldspar, 25 wt.% silica, 4 wt.% of Bauchi clay, and 1 wt.% bone ash sintered at 1200oC gave the best properties and has the potential to be used in dental restoration.

Effect of feldspar and bentonite as soil amendments and foliar silicon application on soil physical properties and maize productivity in sandy soil El-Edfawy, Y. M. and Fanous, N. I. Soil, Water and Environment Research Institute, Agric., Res. Center, Giza, Egypt.

Effect of feldspar and bentonite as soil amendments and foliar silicon application on soil physical properties and maize productivity in sandy soil El-Edfawy, Y. M. and Fanous, N. I. Soil, Water and Environment Research Institute, Agric., Res. Center, Giza, Egypt.

Effects of feldspar and salinity on the mineral sequestration capacity of CO2 in high-salinity aquifers

Mineral sequestration of CO2 is considered to be the safest mechanism in the long-term storage of CO2 in deep saline aquifers. This study aims to investigate the effect of feldspar and salinity on the mineral sequestration capacity of CO2 in deep high-salinity brine aquifers by taking Jiangling Depression of Jianghan Basin for instance. Numerical simulation on the long-term geochemical reaction and transport was performed by taking TOUGHREACT as the simulation tool. Simulation results indicate that the effect of feldspar on the mineral trapping capacity of CO2 does not depend on the total content of feldspar, but depends on feldspar type and relative content. With Mg-rich minerals such as chlorite or dolomite present, the mineral composition abundant in K-feldspar is less favorable for the mineral sequestration capacity of CO2 for the reason that a large amount of illite precipitates, consuming a lot of Al3+ in the aqueous solution, thereby limiting the precipitation of dawsonite, especially for the high-temperature sedimentary environment. In addition, the effect of salinity on the mineral sequestration capacity of CO2 represents two aspects: one for the longer migration distance due to the lower solubility of higher salinity and the other for CO2 mineral trapping capacity per 1 m3 medium which is not in simple decreased with salinity, depending on K-feldspar present or not. For the mineral composition with K-feldspar present, CO2 mineral trapping capacity decreases with salinity, while with albite instead of K-feldspar, it increases with salinity owing to more precipitation of dawsonite.

The effect of feldspar and kaolin on mechanical performance of SBR/LDPE composites

Background Feldspar and kaolin was ball milled at 320 rpm for hours with the aid of a dry grinding agent. Both minerals were combined with inorganic salt namely sodium chloride as a grinding agent. The grinding agent and mineral were mixed at the ratio of 1:1.

Preparation and Characterization of Polycrystalline Cubic Boron Nitride (PcBN) Compacts by a Pressureless Sintering Process

A novel cost-effective pressureless sintering method has been developed to prepare polycrystalline cubic boron nitride (PcBN) compacts. The effect of feldspar as sintering aids was analyzed in this paper. Various amounts of feldspar from 5 to 15 wt% were added to cBN powders, and the pressureless sintering was conducted at temperatures ranging from 900°C to 1200°C under an air atmosphere. The microstructure, phase, density and microhardness of the as-obtained PcBN compacts were measured and correlated to amounts of Si added and to sintering temperatures. The sample showed superior sintering behavior in comparison to those fabricated using hot pressed sintering. The results of X-ray diffraction (XRD) and scanning electron microscopy (SEM) showed that feldspar diffused homogeneously and tightly bonded with cBN. But hBN appeared when the sintering temperature even at 900°C, which dramatically affected the property of PcBN compacts. A PcBN compact with a relative density of 91% was obtained at 1100°C and its microhardness was as high as 1000HV.

Effect of feldspar concentrate on the chemical resistance of acid-resistant materials prepared on the basis of argillaceous materials of different chemical and mineral composition

Research shows that introduction of feldspar concentrate into the composition of ceramic mixes improves mullite crystallization, and this promotes an increase in the acid resistance of refractory materials. An increase in iron oxide content reduces the acid resistance of refractory materials since it does not promote an improvement in mullite lattice crystallization.

Effect of feldspar concentrate on processes that occur during firing of acid-resistant materials based on nonferrous metallurgy concentration waste materials and pyrophyllite

Studies demonstrate that with a firing temperature of 1150°C feldspar grains in acid-resistant materials change very weakly, and they are mainly only vitrified along borders. An increase in firing temperature to 1200°C promotes an increase in glass content. With a firing temperature of 1250°C feldspar grains are entirely replaced by glass, penetrated by acicular mullite crystals.

A Comparative Study on Curing Characteristics, Mechanical Properties, Swelling Behavior, Thermal Stability, and Morphology of Feldspar and Silica in SMR L Vulcanizates

Comparison studies on effects of feldspar and silica (Vulcasil C) as a filler in (SMR L grade natural rubber) vulcanizates on curing characteristics, mechanical properties, swelling behavior, thermal analysis, and morphology were examined. The incorporation of both fillers increases the scorch time, t 2, and cure time, t 90, of SMR L vulcanizates. At a similar filler loading, feldspar exhibited longer t 2 and t 90 but lower values of maximum torque, MHR, and torque difference, MHR–ML than did silica-filled SMR L vulcanizates. For mechanical properties, both fillers were found to be effective in enhancing the tensile strength (up to 10 phr), tensile modulus, and hardness of the vulcanizates. However, feldspar-filled SMR L vulcanizates showed lower values of mechanical properties than did silica-filled SMR L vulcanizates. Swelling measurement indicates that swelling percentages of both fillers-filled SMR L vulcanizates decrease with increasing filler loading whereas silica shows a lower swelling percentage than feldspar-filled SMR L vulcanizates. Scanning electron microscopy (SEM) on fracture surface of tensile samples showed poor filler–matrix adhesion for both fillers with increasing filler loading in the vulcanizates. However, feldspar-filled SMR L vulcanizates showed poorer filler–matrix adhesion than did silica-filled SMR L vulcanizates. Thermogravimetric analysis (TGA) results indicate that the feldspar-filled SMR L vulcanizates have higher thermal stability than do silica-filled SMR L vulcanizates.

The change of phase composition in kaolinite- and illite-rich clay-based ceramic bodies

Raw material for ceramics consists mainly of kaolinite, illite, quartz and feldspar. Three representative clays, a high kaolinitic (HB), illitic- and quartz-rich (KW) and naturally mixed kaolinite–illite (P1) clays of Westerwald area, were chosen for this study [Kromer, H., 1980. Tertiary clays in the Westerwald area. Geol. Jb. D. Rhei D Hanover, 69–84]. The largest and oldest clay mining area of Germany is in the Westerwald area. These clays were mixed with each other and also with K, and Ca–Na feldspar. The high temperature phases of the mixed bodies were of three groups: crystalline phase, amorphous/glassy phase and porosity. The aim of this study was to determine: (1) the effect of kaolinite–illite–quartz ratios, (2) the effect of heat treatment and (3) the effect of feldspar on the fired mineralogy of the fired products. The crystalline phases are cristobalite, mullite, quartz, hematite and anatase. The bodies consist of crystalline phases such as quartz, mullite and cristobalite in a composite structure where crystals and pores are often embedded in amorphous/glassy phase. The formation of mullite and cristobalite is very distinctive in kaolinitic clay, and the structure is dominated by the spiky primary mullite. In the illite/sericite-rich mixtures, the high K content causes a large amount of melt superimposed on the mullite formation. The cristobalite formation is completely suppressed in illite/sericite-rich bodies. After dehydroxylation, metakaolinite and illite/sericite anhydride structures are formed. The persistence of illite/sericite anhydride peaks above 950 °C in KW clay indicates the presence of sericite/muscovite mineral. The disappearance temperatures and firing behaviour of K and Ca–Na feldspar observed within the XRD patterns of mixed bodies are different. K feldspar lines disappear earlier in HB bodies than in KW bodies, but Ca–Na feldspar shows a reverse behaviour. While Ca–Na feldspar peak intensity gradually decreases but persists at 1150–1250 °C, K feldspar suddenly disappears at 1150 °C.

00/02880 Effect of feldspar concentrate and of fly ash on the temperature coefficients of linear expansion of facing tiles

00/02880 Effect of feldspar concentrate and of fly ash on the temperature coefficients of linear expansion of facing tiles

The effect of feldspar on quartz-H2O−CO2 dihedral angles at 4 kbar, with consequences for the behaviour of aqueous fluids in migmatites

An investigation was made of the effect of trace amounts of feldspar (Na and/or K) on dihedral angles in the quartz-H2O−CO2 system at 4 kbar and 450–1050°C. Quartz-quartz-H2O dihedral angles in feldspar-bearing quartz aggregates are observed to be the same as those in pure quartz aggregates at temperatures below 500°C. Above this temperature, they decrease with increasing temperature until the solidus. The final angle at the inception of melting is about 65° for microcline-quartz-H2O and microcline-albite-quartz-H2O, and much less than 60° (the critical value for formation of grain-edge fluid channels in an isotropic system) for the albite-quartz-H2O system. CO2 was observed to produce a constant quartz-quartz-fluid dihedral angle of 97° in feldspar-bearing quartz aggregates at all temperatures studied. Also examined were the dihedral angles for the two co-existing supersolidus fluids in quartz aggregates. In all systems the quartz-volatile fluid angle is greater than 60°, whereas the quartz-melt angle is lower than 60°. Both supersolidus angles decrease with increasing temperature. The transition from nonconnected to connected porosity with increasing temperature observed in the quartz-albite-H2O system some tens of degrees below the solidus (termed a permeability transition), if a common feature of rocks near their melting points, will play an important role in controlling the permeability of high-grade rocks to aqueous fluids.

A comparison of quartz c-axis preferred orientations in experimentally deformed aplites and quartzites

The effect of feldspar on the development of quartz c-axis preferred orientations was investigated by experimentally deforming aplite (30% quartz) and pure quartzite under equivalent conditions and comparing the quartz c-axis patterns. Axial compression experiments were performed at temperatures of 800 and 900°C, strain rates of 10 −6 and 10 −5 s −1 , and a confining pressure of 1500 MPa. Under these conditions, both quartz and feldspar deform by dislocation creep with only minor syntectonic recrystallization. The quartz c-axis preferred orientations produced in the two rock types at equivalent deformation conditions and quartz grain strains were found to be essentially identical in pattern and strength. These results indicate that the presence of feldspar has little or no effect on the operative slip systems in adjacent quartz grains in quartzo-feldspathic rocks, and that quartz c-axis preferred orientation analyses can be performed on a wide range of crustal rock types.

Effect of Feldspar on the Properties of Bentonite Bonded Molding Sand at Elevated Temperatures

Effect of Feldspar on the Properties of Bentonite Bonded Molding Sand at Elevated Temperatures

INVESTIGATION OF FELDSPAR AND ITS EFFECT IN POTTERY BODIES*

The history and purpose of the investigation are outlined and reports are made on (1) fineness determinations, chemical analyses, softening range, softening points, “true” specific gravity, thermal expansion, and petrographic analyses of the individual feldspars; (2) the results of porosity, volume shrinkage during firing, color and translucency, mechanical strength, petrographic analyses, effect of feldspar used on relative “glaze fit,” thermal expansion, and elasticity determinations on vitreous and semivitreous bodies in which feldspar is the only variable component.