Mass Fraction Of Al2O3 Research Articles

Microstructure, corrosive wear and electrochemical properties of Al2O3 reinforced FeAl coatings by laser cladding

PurposeThis study aims to investigate the influences of Al2O3 mass fraction on the corrosive wear and electrochemical behaviors of FeAl–xAl2O3 coatings.Design/methodology/approachFeAl–xAl2O3 coatings were prepared on S355 steel by laser cladding to improve its corrosive wear and electrochemical properties.FindingsThe average coefficients of friction and wear rates of FeAl–xAl2O3 coatings are decreased with the Al2O3 mass fraction, and the Al2O3 plays a positive role in the corrosion wear resistance. Moreover, the charge transfer resistance of FeAl–xAl2O3 coatings is increased with the Al2O3 mass fraction, showing the FeAl–15%Al2O3 coating has the best corrosion resistance. The findings show the corrosion resistance of FeAl–15%Al2O3 coating is the highest among the three kinds of coatings.Originality/valueAl2O3 was first added into FeAl coatings to further improve its corrosive wear and electrochemical properties by laser cladding.

Microstructure, corrosive-wear and electrochemical performance of laser cladded NiTi–xAl2O3 coatings in 3.5%NaCl solution

PurposeThe aim of this study is to investigate the effects of Al2O3 mass fraction on the corrosive-wear and electrochemical performance of NiTi coating in 3.5% NaCl solution.Design/methodology/approachThe NiTi–xAl2O3 coatings were fabricated on S355 steel by laser cladding, and their corrosive-wear and electrochemical performance were investigated using a wear tester and electrochemical workstation, respectively.FindingsThe wear rates of NiTi–5%Al2O3, –10%Al2O3 and –15%Al2O3 coatings are 82.33, 54.23 and 30.10 µm3 mm−1 N−1, respectively, showing that the wear resistance of NiTi–15%Al2O3 coating is the best. The wear mechanism is abrasive wear, which is attributed to the increase of coating hardness by the Al2O3 addition. The polarization resistance of NiTi–5%Al2O3, –10%Al2O3 and –15%Al2O3 coatings is 3,639, 5,125 and 10,024 O cm2, respectively, exhibiting that the NiTi–15% Al2O3 coating has the best corrosion resistance.Originality/valueThe roles of Al2O3 in the corrosive-wear and electrochemical performance of NiTi–xAl2O3 coating were revealed through the experimental investigation.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-02-2024-0044/

Effect of calcium treatment on evolution of inclusions in low-carbon aluminum-killed steel

Based on the steel samples collected from low carbon aluminum-killed steel at ladle furnace start, end of ladle furnace heating, ladle furnace end and tundish pouring process for inclusions analysis, the influence of calcium treatment on the evolution of inclusions in steel from ladle furnace refining to continuous casting was investigated under the condition of using Al2O3-lining ladle. The results show that when calcium treatment is not used, the inclusions in steel are mainly Al2O3 and MgO-Al2O3 spinel, and the mass fraction of Al2O3 in the inclusions composition is ≥90% from ladle furnace refining to continuous casting. After calcium treatment is carried out, the types of inclusions in steel are mainly MgO-Al2O3-CaS (-CaO) inclusions, in which the content of Al2O3 and CaS is higher than the samples without calcium treatment, and low-melting point calcium-aluminate inclusions were not found in the samples. The average size of inclusions in the steel was similar for both processes during ladle furnace refining, but the number density of inclusions in the steel increased significantly after calcium treatment. At the end of LF, the number density of inclusions in the calcium-treated is about twice that of the non-calcium-treated.

Influence of Slag Chemistry on the Dissolution of FeCr<sub>2</sub>O<sub>4</sub> in CaO–SiO<sub>2</sub>–Al<sub>2</sub>O<sub>3</sub>–MgO Slag with Graphite Crucible

The effect of Al2O3 and SiO2 content and basicity (w(CaO) + w(MgO)/w(SiO2) + w(Al2O3)) on the chromite ore dissolution in CaO–SiO2–Al2O3–MgO slag system was studied under the condition of 1550°C. The results show that the increase of basicity (R = 0.54, 0.67, 0.82) results in the reduction of the dissolved amount and dissolution rate of chromite ore in the slag. The dissolved amount of Cr in lower basicity slag (R = 0.54) is about 1.5 to 2 times higher than that in higher basicity slag (R = 0.67, R = 0.82). The dissolved amount of Cr tends to increase when the Al2O3 mass content decreases from 20% to 15%. While as the Al2O3 mass fraction continues to decrease from 15% to 10%, the dissolved amount begins to decrease. This may be related to the viscosity of the slag. The spinel phase tends to form on the surface of the unreacted FeCr2O4, thus hindering the further dissolution of FeCr2O4. After starting to dissolve, the FeCr2O4 decomposes into FeO and Cr2O3 dissolving in the slag. The FeO in the slag is preferentially reduced to metal iron attached to the surface of the FeCr2O4. The main forms of Cr element in the slag are CrO and Cr2O3, and the proportion of these two depends on the composition of the slag and the experimental environment. The proportion of CrO in the slag with lower basicity is larger. In the experiment, the maximum solubility of FeCr2O4 in 60 min was obtained in the slag system with 45% SiO2, 15% CaO, 20% Al2O3 and 20% MgO.

Deep Understanding of the Mechanism and Thermophysical Properties of Prepared Nanofluids Lube Oil Stock-60 with Al2O3 NPs

Iraqi petroleum refineries produce large quantities of base lubricating oils (lube oils). Managing the influence of nano-additives on the lube oil nanofluids is required deep understanding to explain the resulting new specifications of produced nano-lubricants. The present study investigated the effect of Al2O3 NPs addition on the thermal properties of lube oil stock-60. Different mass additions of 0.25, 0.65, 1.05, 1.45, and 1.85 wt.% of Al2O3 NPs at operating temperatures of 20-50°C were evaluated. Also, the thermal conductivity coefficient of the prepared nanofluid was studied at the full range of the experimental temperatures (20-50°C). It was noted that the addition of Al2O3 NPs improved the thermal properties of the prepared nano-lubricant due to the high thermal conductivity of the added Al2O3 NPs. Moreover, the greatest improvement in the thermal conductivity of modified nano-lubricating oil was 13.02% at added Al2O3 mass fraction of 1.85%. The results indicated that the viscosity index of the prepared nano-lubricant was improved dramatically with Al2O3 NPs addition increase at measured standard temperatures of 40 and 100°C. The viscosity index of lubricant nanofluid is increased up to 2.46% at a weight fraction of 1.85%. The flashpoint increased by 1.33, 3.54, 5.75, 7.52, and 9.73% for mass fraction of 0.25, 0.65, 1.05, 1.45, and 1.85 wt.%, respectively. Furthermore, the highest flashpoint value was 248oC of prepared nanofluid lube oil with 1.85 wt.% of Al2O3 NPs. Finally, the produced nano-lubricating oil has high operating quality with economic feasibility. Furthermore, an accurate correlation for predicting the viscosity of both types of nano-lubricants was provided.

A study on the possibility of processing quartz-sericite ore of the Ha Tinh deposit in Vietnam

Sericite has extensive applications due to its specific physicochemical and insulating properties. The total output of sericite products is currently around 350 thousand tons per year and tends to increase by 1–3 % annually. In the Vietnamese province of Ha Tinh, sericite is concentrated in several economic ore bodies. The results of X-ray diffraction, mineralogical, and petrographic analyzes have demonstrated that quartz, sericite, and potassium feldspar account for 97–99 % of the original ore volume. Mineral aggregates are mainly represented by closely intergrown microparticles. The results of process experiments have shown that high-grade sericite concentrates may be recovered from the ore by selective grinding and classification in hydrocyclones. In 20 μm separation, the sericite concentrate yield was 26.94 %, which is 7.48 % higher as compared to 10 μm separation (19.46 %). The concentrate grade, however, was somewhat reduced: the mass fraction of SiO2 in the –20 μm concentrate (52.44 %) was 2.83 % higher than that in the –10 μm concentrate (49.61 %) and the mass fraction of Al2O3 was 1.67 % lower in the –20 μm concentrate (32.76 %) than in the –10 μm concentrate (34.43 %). Selective flotation of –100+10 μm sericite middlings has confirmed the possibility of recovering granular sericite into a concentrate complying with the raw materials standards of a number of industries.

Effects of Al2O3 mass fraction on microstructure and friction–wear performance of laser cladded Fe90 alloy coating

Purpose This paper aims to improve the friction reduction and wear resistance of Fe90 alloy coating by the addition of Al2O3. Design/methodology/approach Fe90 alloy coatings with the different Al2O3 mass fractions were prepared on Q235 steel by laser cladding (LC). The morphologies, phases and hardness of Fe90 alloy coating were analyzed using a scanning electron microscope (SEM), X-ray diffraction (XRD) and microhardness tester, respectively. The effects of Al2O3 mass fraction on the coefficient of friction (COF) and wear rates of Fe90 alloy coating were investigated using a friction tester, and the wear model was built to discuss the wear mechanism of Al2O3-reinforced Fe90 alloy coating. Findings The results show that the large number of Fe carbides is generated on the Fe90–Al2O3 coatings by the effect of laser high energy, and the hardness of Fe90–coating is 806 HV0.5, which is 4.48 times of substrate. The average COFs of Fe90–Al2O3 alloy coatings decrease from 0.73 to 0.55, and the wear rates are also reduced from 447.78 to 274.63 µm3•s–1•N–1 by the addition of Al2O3. The Fe90–6% Al2O3 coating presents the highest wear resistance among the three kinds of coatings, and the wear mechanism is abrasive wear and micro-cutting wear. Originality/value The Al2O3-reinforced Fe90 alloy coating was first fabricated by laser cladding, and the effect of Al2O3 on the friction-wear performance of Fe90 alloy coating was investigated.

Cu-ZnO@Al2O3 hybrid nanoparticle with enhanced activity for catalytic CO2 conversion to methanol

A facile approach is demonstrated for the fabrication of Cu-ZnO-based hybrid nanostructures for the catalytic CO2 conversion to methanol. The method combines colloid stabilization of Al2O3 nanoparticles (as support material) and controlled co-precipitation of Cu (active metal) and ZnO (promoter) onto the Al2O3 nanoparticles. Complementary approaches, including X-ray diffractometry, Brunauer-Emmett-Teller surface area analysis, N2O pulse chemisorption, CO2-based temperature-programmed desorption, transmission electron microscopy coupled with energy dispersive spectroscopy, inductively coupled plasma optical emission spectrometry and thermal gravimetric analysis are employed for the characterization of catalyst materials. The results show a successful synthesis of ultrafine Cu-ZnO nanocrystallites deposited on the Al2O3 nanoparticle clusters (Cu-ZnO@Al2O3). Hybridization with Al2O3 nanoparticles enhanced metal dispersion and number of basic sites of the Cu-ZnO-based nanocatalyst. Aminosilane-based surface functionalization on the Al2O3 nanoparticle increased metal surface area in the hybrid nanostructure. The CO2 conversion catalyzed by the synthesized Cu-ZnO@Al2O3 was shown to be proportional to active surface area of the hybrid nanostructure. An optimum selectivity of the synthesized catalyst was identified (≈47–49%) when the mass fraction of Al2O3 was (35–36) %, in correspondence to the highest moderate basicity of the synthesized hybrid nanostructures. The highest yield of methanol achieved 12989 ± 2007 µmolg−1 h−1 by the developed Cu-ZnO@Al2O3. Our work demonstrates a prototype study of fabricating high-performance hybrid nanocatalyst with the support of mechanistic understanding in material synthesis for the synergistic catalysis of CO2 hydrogenation to methanol.

Thermal-hydraulic analysis of Al2O3 nanofluid as a coolant in Canadian supercritical water reactor by porous media approach

In this study, thermal-hydraulic analysis of Canadian Supercritical Water Reactor (Canadian SCWR) with nanofluid coolant has been done by porous media approach. In the applied analysis the derived conservation equations of mass, momentum and energy for coolant and conduction heat transfer equation for fuel and clad were discretised by finite volume method and solved numerically using C# program. Nanofluid coolant with various concentration of Al2O3 (Alumina) nanoparticle (up to 40% mass fraction) was selected for this study. Since in Canadian SCWR coolant and moderator are separated, higher mass fraction of nanofluid can be applied in this concept. The achieved results show that by increasing Al2O3 mass fraction, coolant heat transfer coefficient and average coolant temperature grow up in the middle of the core and pressure drop will be raised. Average clad and fuel temperature in the core was calculated. The results show that by using Alumina nanofluid with 40% nanoparticle mass fraction, maximum clad wall and fuel temperatures decrease about 20 °C and 30 °C respectively.

High-efficiency and ultra-thin electromagnetic wave absorption xAl2O3–(1 − x)Sr0.85Gd0.15TiO3 ceramics in X-band

xAl2O3–(1 − x)Sr0.85Gd0.15TiO3(x = 0.2, 0.3, 0.4, 0.5) ceramics were fabricated by hot-press sintering. Their phase composition, morphology, element compositions, conductivity, dielectric properties as well as microwave absorption performance were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), multifunction digital four-probe meter and vector network analysis, respectively. The microwave absorption of the as-prepared xAl2O3–(1 − x)Sr0.85Gd0.15TiO3 ceramics demonstrates excellent microwave absorbability. It is unexpectedly found that with a thickness of only 0.346 mm, xAl2O3–(1 − x)Sr0.85Gd0.15TiO3 (x = 0.2) ceramic exhibits an absorption bandwidth of 3.7 GHz (8.7–12.4 GHz), being consequential to reflection loss less than − 10 dB (over 90% of microwave absorption). It is as well discovered that the minimum reflection loss and absorption peak frequency of xAl2O3–(1 − x)Sr0.85Gd0.15TiO3 (x = 0.3) with a thickness of 0.436 mm were − 45.43 dB and 11.3 GHz, respectively. The prominent microwave absorption performance of the ceramic with such a thin thickness can be attributed to strong interfacial polarization, dielectric frequency dispersion, and good electromagnetic impedance matching. It indicates that the xAl2O3–(1 − x)Sr0.85Gd0.15TiO3 ceramics with appropriate Al2O3 mass fraction and thickness showing good potential for effective microwave absorbing materials.

Influence of Aging and Mass Fraction of Al2O3 on Mechanical Properties of Al6082/Al2O3 Composite Produced by Stir Casting

The effect of artificial aging on the mechanical properties of Al6082 alloy and Al6082/(2 – 10%)Al2O3 composite produced by stir casting is studied. The structure is studied with the help of a field emission scanning electron microscope (FESEM). The stress-strain curves, the impact energy and the hardness are measured. It is shown that growth in the fraction of the hardening phase and artificial aging (180°C, 2 h) raise the tensile strength, the hardness and the fracture toughness and provide uniform distribution of Al2O3 particles in the matrix.

Thermal properties of a novel form-stable phase change thermal interface materials olefin block copolymer/paraffin filled with Al2O3

Thermal contact resistance (TCR) between the thermal interface materials (TIMs) and the upper and lower contact surfaces plays an important role in the heat dissipation process of electronic devices. Moreover, TCR is mainly affected by temperature, pressure and fluidity of TIMs. When the critical operating temperature of the electronic device is reached, if solid-solid contact between two contact surfaces is changed into solid-liquid contact, TCR will be greatly reduced. Based on this idea, a novel form-stable phase change TIMs is proposed. The thermal conductivity of paraffin wax (PA) is improved by filling Al2O3 particles. The addition of olefin block copolymer (OBC) improves the stability and solves the leakage problem of PA. In addition, the effects of temperature and pressure on the TCR, especially near the phase transition point, are systematically studied. These results confirm that TCR of phase change Al2O3/OBC/PA is very sensitive to temperature. When the temperature rises from 37 °C to 41 °C, TCR of all samples decreases sharply from 10~20 K⋅cm2/Wto 1~2K⋅cm2/W. TCR of all samples decreases slowly with the increase of pressure (10~50 Psi, 45 °C) and is very close to the TCR of common thermal grease. Finally, when the mass fraction of Al2O3 is higher than 60 wt%, the thermal conductivity of the Al2O3/OBC/PA increases sharply with the increase of Al2O3. Therefore, form-stable Al2O3/OBC/PA is an important development direction to solve the heat dissipation in electronic technology.

Formation and Deformation Mechanism of Al2O3-CaS Inclusions in Ca-Treated Non-Oriented Electrical Steels

Industrial trials were performed to study the effect of calcium treatment on inclusions in non-oriented electrical steels. The evolution and characterization of inclusions in both molten steel and rolled steel were investigated, including a thermodynamic analysis using FactSage 7.1. In the Ca-treated steel, alumina inclusions were transformed into Al2O3-CaO-CaS, with a mass fraction of CaO that increased with increasing the Ca/S ratio. Inclusions of Al2O3-CaO-CaS were classified into wrapping and adhesion type according to their morphologies. Adhesion-type Al2O3-CaO-CaS inclusions were observed only in the steel with Ca/S > 0.84. The two types of Al2O3-CaO-CaS inclusions were transformed into Al2O3-CaS with distinctive morphologies. The mass fraction of Al2O3 and CaS in the inclusions was experimentally found to depend on the Ca/S ratio of the steel and confirmed by thermodynamic analysis. The two types of Al2O3-CaS inclusions could hardly be deformed during the hot-rolling process of the steel but showed different deformation behavior during the cold-rolling process of the steel. The component of CaS in the adhesion-type Al2O3-CaS inclusions was more easily separated from Al2O3 and formed a tail along the rolling direction of the steel, while only a little part of the CaS component broke off from the wrapping-type Al2O3-CaS inclusions.

Influence of Al2O3 mass fractions on microstructure, oxidation resistance and friction–wear behaviors of CoCrAlYTaSi coatings

CoCrAlYTaSi coatings with different Al2O3 mass fractions were fabricated on Ti–6Al–4V alloy using a laser cladding (LC). The effects of Al2O3 mass fractions on the microstructure, oxidation resistance and friction–wear performance of obtained coatings were investigated, and the wear mechanisms were also discussed. The results show that the hardness of CoCrAlYTaSi coating increases with the increase of Al2O3 mass fractions, the dendritic structure with the Al2O3 mass fraction of 15% is compactly refined. The diffusion barrier layer of Al2O3 contains Y oxide precipitate, which reduces the oxidation rate and the movement of Ta. The total mass gain per unit area of CoCrAlYTaSi coating with the Al2O3 mass fractions of 15, 30 and 45% is 33.96, 29.82, and 26.27 mg •cm−2, respectively, the oxidation resistance with the Al2O3 mass fraction of 15% is the best among the three kinds of coatings. The average coefficients of friction (COFs) of CoCrAlYTaSi coatings with the Al2O3 mass fractions of 0, 15, 30 and 45% are 1.12, 0.17, 0.23, and 0.35, respectively, and the corresponding wear rates of are 1.59 × 10−4, 1.02 × 10−4, 0.54 × 10−4, and 0.3 × 10−4 mm3 N−1•m−1, respectively, the wear mechanism is abrasive wear and micro–cutting.

Formation Mechanism of Large Inclusions in 80t 20Cr–8Ni Stainless Steel Casting for Nuclear Power

80t 20Cr–8Ni stainless steel castings are used to manufacture pump casing for nuclear power. However, large inclusions are usually observed on an ingot surface, which cause failure in penetrant testing. To clarify the formation mechanism of large inclusions, the evolution, growth, and aggregation of inclusions during the argon oxygen decarburization furnace (AOD) refining–Ca treatment–ingot casting process are investigated. The results show that Al2O3 clusters >50 μm and single Al2O3 particles >10 μm are typical large inclusions on ingot surface. After aluminum addition in AOD, typical inclusions are spinel or dual‐phase CaO–MgO–Al2O3. After Ca treatment, typical inclusions are liquid or dual‐phase CaO–MgO–Al2O3. With temperature decreasing during casting process, the mass fraction of Al2O3 keeps on increasing due to decreasing oxygen and aluminum solubility. It is concluded that Al2O3 is formed during casting process. Single Al2O3 particles grow up to ≥7.5 μm or more. With the size of single Al2O3 particles increasing, Al2O3 clusters are formed mainly through Stokes and turbulent collision. In addition, the aggregation area of single Al2O3 particles and Al2O3 clusters is formed on the surface of ingot.

Experimental investigation toward obtaining a new correlation for viscosity of WO3 and Al2O3 nanoparticles-loaded nanofluid within aqueous and non-aqueous basefluids

In this study, the effect of temperature and mass fraction of Al2O3 and WO3 nanoparticles dispersed in deionized water and liquid paraffin was investigated on dynamic viscosity of nanofluid. The results of the TEM tests showed that the size of Al2O3 and WO3 nanoparticles was ranged from 10 to 60 nm, and the results showed that nanoparticles were semi-spherical. Also the results of DLS and zeta potential tests, respectively, exhibited the uniform size and high stability of the nanoparticles in the basefluid environment. The findings showed that adding a certain amount of nanoparticles to water and liquid paraffin increases dynamic viscosity, and in the case of various shear rates, the viscosity is constant for the water-based nanofluids, which indicates the Newtonian behavior of the nanofluid. In addition, for those prepared by liquid paraffin as a basefluid, the viscosity does not remain constant at different shear rates and at low amount of shear rate the viscosity achieves higher value, indicating non-Newtonian behavior of liquid paraffin-based nanofluids. The results showed that by increasing the temperature in liquid paraffin-based nanofluid the uniformity and linearity of the viscosity curve at various shear rates could be observed, which represents an approach for Newtonian behavior of nanofluid at higher temperatures. These results also showed that with increasing the mass fraction of nanoparticles in water and liquid paraffin, the viscosity increases at different shear rates. Finally, the correlation presented in this study shows that for nanofluid viscosity as a function of nanoparticles load and temperature, the deviation of correlated data from experimental values is less than 10%.

Special vibrocast mullite-siliceous refractories with the given properties for glass melting furnaces

Technologies have been developed for the production of special vibrocast large-sized mullite-siliceous and mullite-siliceous low-cement refractories with specified properties for the laying of side walls and the bottom of glass melting furnaces and other place of applications. The influence of the amount alumina and calcined kaolin fraction 3—0.5 mm on the properties of mass, raw and firing (at temperatures of 1350, 1400, 1450 оC) samples have been researched, and also the flow at vibration has been studied, stages of structure formation and technological factors, providing qualitative vibrocasting of products, have been determined. The developed mullite-siliceous and mullite-siliceous low-cement refractories in terms of properties fully meet the specified requirements: mass fraction of Al2O3 — 52.58 and 53.83 %, SiO2 — 46.11 and 45.19 %, CaO — 0.09 and 1.12 %, Fe2O3 — 1.10 and 1.06 %; apparent density — 2.21 g/cm3, open porosity — 20.2 and 20.3 %, cold crushing strength — 68 and 69 N/mm2, thermal conductivity (at 400—800 оC) — 1.237—1.637 W/(m ∙ K).

Grade Distribution Modeling within the Bauxite Seams of the Wachangping Mine, China, Using a Multi-Step Interpolation Algorithm

Mineral reserve estimation and mining design depend on a precise modeling of the mineralized deposit. A multi-step interpolation algorithm, including 1D biharmonic spline estimator for interpolating floor altitudes, 2D nearest neighbor, linear, natural neighbor, cubic, biharmonic spline, inverse distance weighted, simple kriging, and ordinary kriging interpolations for grade distribution on the two vertical sections at roadways, and 3D linear interpolation for grade distribution between sections, was proposed to build a 3D grade distribution model of the mineralized seam in a longwall mining panel with a U-shaped layout having two roadways at both sides. Compared to field data from exploratory boreholes, this multi-step interpolation using a natural neighbor method shows an optimal stability and a minimal difference between interpolation and field data. Using this method, the 97,576 m3 of bauxite, in which the mass fraction of Al2O3 (Wa) and the mass ratio of Al2O3 to SiO2 (Wa/s) are 61.68% and 27.72, respectively, was delimited from the 189,260 m3 mineralized deposit in the 1102 longwall mining panel in the Wachangping mine, Southwest China. The mean absolute errors, the root mean squared errors and the relative standard deviations of errors between interpolated data and exploratory grade data at six boreholes are 2.544, 2.674, and 32.37% of Wa; and 1.761, 1.974, and 67.37% of Wa/s, respectively. The proposed method can be used for characterizing the grade distribution in a mineralized seam between two roadways at both sides of a longwall mining panel.

Effect of chemical composition on the surface charge property and flotation behavior of pyrophyllite particles

The surface charge property and chemical composition are important for flotation investigation. First, the mineral phase and morphology of different pyrophyllite samples were analyzed. The isoelectric points of different pyrophyllite particles also were determined. Moreover, the effect of chemical composition on flotation recovery of pyrophyllite particles was studied. The isoelectric point (iep) of pyrophyllite particles shows negative correlation with the mass fractions of SiO2 and Na2O. At the point of zero charge of edge plane of pyrophyllite, the zeta potential of pyrophyllite particles displays negative correlation with mass fraction of SiO2. While it shows positive correlation with mass fraction of CaO and TiO2. Additionally, the flotation experiments of the pyrophyllite particles were conducted and the results showed that the flotation recovery has a positive correlation with mass fraction of SiO2, while negative correlation with mass fraction of Al2O3, TFe, and iep. Therefore, the content of SiO2 is beneficial to the flotation of the pyrophyllite particles.

Investigation on High-Temperature Creep Properties of High-Alumina Bauxite

This paper studied the high temperature creep properties of high-alumina bauxite (the mass fraction of Al2O3 in the new ore is about 78, the following abbreviations for Al2O3~78). The results indicated that the Al2O3~78 high-alumina bauxite mainly are corundum phase after high temperature sintered.When the temperature is 1100°C, corundum exists as crystal phase and the connections between grains are directly. The creep resistance of samples is very good at this temperature and the creep rate of 50 hours heat preservation is-0.266%. When the temperature is 1200°C, liquid phase starts to produce in a large number and the creep rate in 50 hours heat preservation is-1.589%. When the temperature is 1300°C, because of the further increase on the amount of liquid phase and wetting coated corundum particle, the direct connections between corundum particles are broken and the creep resistance is greatly reduced, the creep rate in 50 hours heat preservation is-4.088%. The creep curve fitting after 25 hours indicated that the creep property shows linear relations in three different temperatures after 25 hours. When the temperature is 1200°C and 1300°C, the creep variables arise rapidly in linear which declare the creep resistance of corundum is poor and increasing with temperature go up, more corundum phase is covered by glass phase and the creep resistance reduces dramatically.