Novelty phase synthesis mechanism and morphology in resin-bonded Al–Al2O3–TiO2 composites at high temperatures under flowing N2

An Al–AlN core–shell structure is beneficial to the performance of Al–Al2O3 composites. In this paper, the phase evolution and microstructure of Al–Al2O3–TiO2 composites at high temperatures in flowing N2 were investigated after the Al–AlN core–shell structure was created at 853 K for 8 h. The results show that TiO2 can convert Al into Al3Ti(~1685 K), which reduces the content of metal Al and rearranges the structure of the composite. Under N2 conditions, Al3Ti is further transformed into a novelty non-oxide phase, TiCN. The transformation process can be expressed as follows: Al3Ti reacts with C and other carbides(Al4C3 and Al4O4C) to form TiCx(x < 1). As the firing temperature increases, Al3Ti transforms into a liquid phase and produces Ti(g) and TiO(g). Finally, Ti(g) and TiO(g) are nitrided and solid-dissolved into the TiCx crystals to form a TiCN solid solution.

Development and Application of Chrome-free Refractory Materials for RH Degasser

The research progress and industrial application of chrome-free refractories for RH degasser were introduced in the paper.It is proved that unburned magnesia-spinel refractories used for RH throat and snorkel in Baosteel have longer service life compared with traditional direct bonded fused magnesia-chrome materials.The new developed chrome-free unburned magnesia-spinel composite can fully meet the present demand for RH operation and can be applied extensively for RH processing.At present,instead of chrome-containing materials,chrome-free refractories have been applied widely for RH in Baosteel.Super low carbon MgO-C material with high mechanical properties at mild and high temperatures can be an alternative chrome-free material for RH.

Research on Copper Matte Corrosion to Periclase-spinel Refractories

Effects of TiO2 or ZrO2 addition on corrosion resist; ance of periclase -spinel refractories to copper matte at different temperatures were investigated using static crucible method, and the results were compared with those of fused rebonded magnesite -chrome bricks. The chartges in chemical compositions and microstructure in different zones of the specimens after corrosion tests were studied by means of EDAX and SEM. The results show that ： （ 1 ） the reaction between periclase - spinel refractories and copper matte is very weak with the reaction layer thinner than 1 mm. Penetration is the main cause of copper matte corrosion and the penetration depth increases with temperature rising. When temperature exceeds 1200 ℃ , the penetration depth increases significantly; （2） appropriate TiO2 addition can improve penetration resistance （even better than that of magnesia chrome brick）, the optimum addition is 2 %. But ZrO2 has no remarkable effect on penetration resistance to copper matte of periclase - spinel refractories ; （ 3 ） SEM and EDAX analysis indicates that, Cu2S penetrates much further into the specimens than FeS.

High Chrome Containing Refractories for Coal Slurry Gasifier

Water, oxygen and coal are converted into CO, H2, methane in the coal slurry gasifier. Under the condition of high temperature and high pressure, high chromecontaining refractories are used as hot face lining. The collapse of refractories from corrosion and spalling is mainly attributed to liquid deslagging. Refractories for coal slurry gasifier, destruction mechanism and solutions are analyzed.

Influence of Nano-Al_2O_3 on Properties of Magnesia Chrome Refractories

Magnesia chrome bricks were prepared with fiLsed MgO- Cr2 O3 synthesized material, fused magnesite and ：hrome ore as main starting materials. Nano-Al2O3 was tdded into refractories （ 2% , 4% and 6% in mass ） ;ubstit,ting for Al203 micropowder. After m＆ing and ;haping, the bricks were fired at 1 550 ℃, 1 600 91℃, t 650 ℃ and 1 750℃, respectively. The microstruc-ure , sintering property, mechanical properties, thermal ;kock resistance and shtg resistance of the specimens with he addition of nano-Al2O3 were investigated. The results indicate that the performance of brick with 4 mass% of nano-Al2O3 is greatly improred afier firing at 1 650 ℃.

Hydrothermal Synthesis and Visible-light Photocatalytic Activities of SnS_2 Nanoflakes

SnS2 nanoflakes were successfully synthesized via a simple hydrothermal process. The as-prepared SnS2 samples were characterized by X-ray diffraction（XRD）, scanning electron microscopy（SEM）, nitrogen adsorption-desorption isotherms, and UV-vis diffuse reflectance spectroscopy（DRS）. The photocatalytic activities of the as-prepared SnS2 nanoflakes under visible light irradiation（λ〉420 nm） were evaluated by the degradation of rhodamine B（Rh B）. The effect of hydrothermal temperatures on the photocatalytic efficiency of as-prepared SnS2 nanoflakes was investigated. The experimental result showed that SnS2 nanoflakes synthesized at the temprature of 160 o had higher photocatalytic efficiency and good photocatalytic stability.

Role of in-situ Formed Nonoxides Bonded Phases in Property Improvement of Alumina ULC Castables

In order to enhance performance of pre-cast shapes of alumina based castables, the present work explored the approach of forming in-situ bonding phases by incorporating Si powders and then heating in carbon, embedded atmosphere. Using tabular alumina as aggregates, tabular alumina, SiC powders, Si powders, calcium aluminate cenwnt, microsilica and ultrafine α-A12 03 powders as matrix, alumina based ultra low cement （ULC） castables were prepared. Influences of Si powder addition at O, 4% , 6% , 8% alul 10% （in nutss ） on regular properties, cold modulus of rupture （CMOR）, hot modulus of rupture （HMOR）, thermal shock resistance （TSR） and microstructure of the castables after carbonization were investigated. After incorporation of Si powders and carbon embedded heating, the in-situ mullite and nonoxide phases such as SiAION and SiC can be fornwd by oxidation, nitridation or carbomlzation reaction. HMOR and TSR of the castables with in-situ nonoxides bonding are obviously improted. After carbon embedded heating, the HMOR at 1 400 ℃ increases from 1.6 MPa to 8. 3 MPa, and the residual CMOR ratio after thermal shock increases from 64. 9% to 137. 9% when Si addition increases from 0 to 10%.

Properties of Magnesia-Hercynite Brick

Properties of magnesia-hercynite brick were studied. The coatability, thermal shock resistance, corrosion resistance to cement clinker and thermal conductivity were compared with those of magnesia-chrome brick and magnesia-spinel brick used widely in sintering zone of cement rotary kiln. The result shows that magnesia-hercynite brick is better than magnesia-chrome brick in thermal chock resistance and corrosion resistance to cement clinker, is similar to magnesia-chrome brick and is better than magnesia-spinel brick in coatability and thermal conductivity.

Analysis of Spent High Chrome Brick in Slagging Gasifier

Wear of the spent high chrome brick in slagging gasifier was studied. The result shows that erosion and spalling are the m, ain wear mechanism of high chrome brick and the CaO content of coal slag is crucial to wear of high chrome brick.

Application of Wedge Splitting Test in Refractories

This paper mainly describes fracture mechanics and the application of the newly developed wedge splitting test in evaluating the thermal shock resistance of refractories. It is necessary to evaluate fracture properties owning to the heterogeneity of refractories.

Effect of Micropowder Introduction on Synthesis of SiAlON-bonded SiC Products

This work aims at preparing SiAlON-bonded SiC products with high SiAlON contents.Silicon carbide fines,micropowders of Si,Al and alumina with different activities were premixed in a ball mill to obtain different composite micropowders.Then silicon carbide particles,the composite micropowders and binder were wet mixed.After shaping the specimens were fired under insulation from direct flame in a shuttle kiln at 1450℃in nitrogen atmosphere.The chemical composition,microstructure,pore size distribution and CO resistance of the prepared specimens were tested.The results showed that:after introducing high-activity micropowder additives the SiAlON content grows from 14.8 mass%to 23.5 mass%;the amount of unreacted alumina and silicon nitride in the specimens falls from 8.78 mass%to 1.79 mass%;micropores with size under 1m increase from 30%to 68%;CO resistance reaches level A.

Effect of Magnesia-Chrome Synthetic Materials on Magnesia-Alumina-Chrome Ramming Mixes

Magnesia-alumina-chrome ramming mixes with same chemical compositions were prepared by using different raw materials such as fused magnesia-chrome synthetic materials and sintered one, wasted bricks and magnesia-alumina spinels. Their physical properties were tested and microstructures were analyzed. The results show that the ramming mixes made of different raw materials bring about different microstructures and properties although the mixes have the same chemical composition, binder content and aggregate size composition.