Papers by Author: Rong Lin Wang

Abstract: In this experiment, preparation of samples were based on original ratio of bauxite matrix Al₂O₃-SiC-C castable for iron runner, and partial bauxites of size 8-5 mm, 5-3 mm, 3-0 mm and <0.074 mm were replaced by the same size granular recycling Al₂O₃-MgO-C materials from spent ladle bricks, respectively. Si₃N₄ and B₄C were introduced as appropriate additives. Effects of their amount on the performance of Al₂O₃-SiC-C castable for iron runner were investigated by testing on physical properties and erosion resistance of the samples after sintering. The results showed that the introduction of Si₃N₄ and B₄C led to high temperature flexural strength of the recycled castable samples decline, while the right amount could improve the room temperature flexural and pressure strength along with the erosion resistance to blast furnace slag. When introduced 3% of Si₃N₄and 0.3% of B₄C respectively, the comprehensive performance of the samples were the best.

Abstract: In this experiment, preparation of samples were based on original ratio of bauxite matrix Al₂O₃-SiC-C castable for iron runner, and partial bauxites of size 8-5 mm, 5-3 mm, 3-1 mm and 2O₃-MgO-C materials from spent ladle bricks, respectively. Effects of particle size and content of the recycled materials on sintering performance of the castable were investigated. The sintering performance was analyzed by measuring apparent porosity, room temperature flexural strength, room temperature pressure strength and high temperature flexural strength. The results showed that the apparent porosity of the samples overall tended to increase with content of the recycling materials increasing, while room temperature flexural strength, room temperature pressure strength and high temperature flexural strength of the samples reduced gradually. 8-5mm and 5-3 mm particle of 5%-15% the recycling Al₂O₃-MgO-C materials was more suitable for the preservation of high temperature flexural strength and room temperature strength of the samples than 3-1 mm and < 0.074 mm particle.

Abstract: In this experiment, preparation of samples were based on original ratio of bauxite matrix Al₂O₃-SiC-C castable for iron tap channel, and partial bauxites of size 8-5 mm, 5-3 mm, 3-1 mm and 2O₃-MgO-C ladle bricks, respectively. Effects of recycling ladle lining materials on phase composition and microstructure of Al₂O₃-SiC-C castable for iron runner were investigated by XRD, SEM and EDS. The results showed that new phases SiO₂ and (Mg_0.804Ca_0.196)₃Al₂(SiO₄)₃ were formed in the castable at 1450 oC in air atmosphere, and the spherical (Mg_0.804Ca_0.196)₃Al₂(SiO₄)₃ was formed on external surface of recycling Al₂O₃-MgO-C particle. thereinto, SiC oxidation to formed SiO₂ with flow pattern character was key element of the phase (Mg_0.804Ca_0.196)₃Al₂(SiO₄)₃ formation. The more fine and uniform of recycling Al₂O₃-MgO-C particles, the more spherical (Mg_0.804Ca_0.196)₃Al₂(SiO₄)₃ was formed in recycling Al₂O₃-SiC-C castable. Internal structure of theirs samples exhibited looser state with content increasing of recycling ladle lining materials.

Abstract: AlN-ZrO₂ system composites were prepared with Ca-stabilized zirconia (Ca-PSZ, particle size d₅₀=29.3 μm) and AlN power (d₅₀=0.5 μm) as raw material, MoSi₂ (d₅₀=2 μm) and Si₃N₄ (d₅₀=44 μm) as additives respectively, in N₂ atmosphere by pressureless sintering at 1600 °C. The phase compositions were investigated by XRD. The sintering performance of the composites was measured by the checking of the bending strength and the apparent porosity of samples. The anti-oxidation performance of the composites was analyzed by the checking of oxidation weight increased of samples. The results showed that phase compositions of the composites consisted of ZrO₂, ZrN, CaAl₁₂O₁₉ and CaA_l2Si₂O₈when the content of AlN was 8 wt %. The additives promoted the sintering of AlN-ZrO₂ system composites. As a result, introduction of the additives increased the oxidation of the composites due to oxidation expansion of phases ZrN.

Abstract: Synthesis process of ZrAl₃O₃N was investigated by non-pressure sintering at 1600 °C in N₂ atmosphere according to five drafted equations. The influences of the atmosphere and material combination on the synthetic effect of ZrAl₃O₃N were preliminarily discussed by XRD. The results showed that atmosphere was a key factor that determined whether ZrAl₃O₃N could be synthesized, i.e. ZrAl₃O₃N could only be synthesized in high purity N₂ atmosphere, and that ZrAl₃O₃N was only synthesized on condition that the raw material composition included both AlN powder and nano-ZrO₂ powder. However, with increasing of AlN content, the XRD peaks of ZrAl₃O₃N and ZrN phase gradually reduced, and pure ZrAl₃O₃N was hardly obtained by in-situ reaction between AlN and ZrO₂ because of generation of ZrN as well.

Abstract: MgO-CaO-ZrO₂ composite materials were prepared in oxidizing atmosphere at 1550 oC with sintered magnesia, calcium oxide and partial stabilized zirconia as raw materials. Sintering performance of the composites was measured by the checking of the bending strength, the apparent porosity, the thermal expansivity and the thermal shock resistance of samples, respectively. The phase compositions and microstructures of the composites were investigated by XRD, SEM and EDS. The results showed that CaZrO₃ phase was formed by high temperture reaction between ZrO₂ and CaO, and phase compositions of the composites consisted of two phases of CaZrO₃ and MgO. The sintering performance of composites were promoted further with increasing the content of ZrO₂ due to the volume expansion caused by the reaction of the added ZrO₂ and CaO to form CaZrO₃ phase in the refractories.

Abstract: AlN-ZrO₂(Ca) composites were prepared with two kinds of Ca-stabilized zirconia (ZrO₂(Ca), i.e Ca-PSZ, particle size d₅₀=65μm and d₅₀=7.5μm) and three kinds of AlN power (d₅₀=15μm, d₅₀=0.5μm and d₅₀=40nm) as raw material in N2 atmosphere by pressureless sintering at 1850 oC. The phase compositions and microstructures of composites were investigated by XRD, SEM and EDS.The sintering performance of the composites was measured by the checking of the bending strength, and the apparent porosity of samples. The results showed that phase compositions of the composites consisted of major phases C-ZrO₂ and AlN and minor phase CaAl₁₂O₁₉. It was harder that AlN-ZrO₂(Ca) composites were sintered than ZrO₂(Ca) material. It was major cause that phase CaAl₁₂O₁₉ formed and its abnormal growed in the boundary layer between AlN particle and ZrO₂(Ca) matrix. With 2mm AlN particles as raw material, AlN-ZrO₂(Ca) composites had better sintering performance when concent of AlN equaled to 8%.

Abstract: AlN-ZrO₂ composites were prepared by hot pressed sintering with AlN particle (d≈2mm, d≈1.5mm and d≈1mm) and ZrO₂ powder as material. Its phase composition, thermal conductivity and sintering performance were investigated by XRD, SEM, EDS and performance testing. The results showed that AlN could be reserved in samples, and the thermal conductivity and the apparent porosity of the samples ascended with increase of the content of AlN, and the bending strength of the samples with same AlN particle occurred change according to V-shape with content of AlN increasing. Thereinto, the thermal conductivity of the samples with 1.5mm AlN was most excellent, amang samples with AlN particle of 2mm, 1.5mm and 1mm, and sintering performance of the samples with 1mm AlN was best. Particle interface of AlN and ZrO₂ was high concentration area of elements Ca and O, and was a structural loose crack area with CaAl₁₂O₁₉ formed. The area is abominable for performances of AlN-ZrO₂ composites such as thermal conductivity, density and strength. It is more appropriate for preparation of AlN-ZrO₂ composites with AlN particle of 1.5mm and 1mm as materials.

Abstract: Influencing effects of additives CaF₂, ZrB₂ and MoSi₂ on sintering performance and oxidation resistance of Zr-Al-O-N composites were investigated. The results showed that additives CaF2, ZrB2 and MoSi₂ were beneficial to improve sintering density of Zr(Ca)-Al-O-N composites, and additives CaF2 and ZrB2 were beneficial to improve obviously bending strength of samples Zr(Ca)-Al-O-N composites and MoSi2 was contrary. After additives CaF₂, ZrB₂ and MoSi₂ were introduced to Zr(Ca)-Al-O-N composites, oxidation resistance of Zr(Ca)-Al-O-N composites was improved, and relative superior or inferior of influence ranking of additives was MoSi₂, CaF₂, and ZrB₂.

Abstract: Zr(Ca)-Al-O-N composites were prepared with ZrO₂(Ca) (i.e Ca-PSZ, d₅₀ < 10 μm) and Al powder (d₅₀ =7.5 μm, 29 μm, and 62 μm) as raw materials by in situ reaction sintering in N₂ atmosphere at 1600 °C. Phase constiturion of the composites was affirmed by XRD and SEM-EDS, and effect of grain size and content of Al powder on sintering performance of the composites was investigated, and oxidation characteristic of the composites were analysed by measure increasing weight of oxidation. The results showed that major phases of the composites composed of (t+c)-ZrO₂, ZrN, ZrAl₃O₃N and CaAl₁₂O₁₉, and Al powder of 5 wt% - 7 wt% d₅₀ =7.5 μm and 3 wt% - 5 wt% d₅₀ =29 μm were suitable for preparation of the composites and bendiing strength of its samples sintered at 1600 °C had 60-90MPa. In atmosphere, oxidation onset temperature of Zr(Ca)-Al-O-N composites were approximately 550 °C, and the end temperature of its oxidening were approximately 950 °C. Treating with antioxidation is a key for application of Zr(Ca)-Al-O-N composites.