PREPATATION OF SPODUMENE-DERIVED LOW EXPANSION COEFFICIENT GLASS CERAMIC IN THE SYSTEM Li_2O-Al_2O_3-SiO_2

In this paper ,spodumene mineral was used as raw material for fabricating glass ceramic with the addition of MgO,ZnO and TiO2,ZrO2. The expansion coefficient of the materials is 5. 5×107/℃ . Also the effects of the heat treatment on the crystallzing behaviour has been discussed by XRD and DTA.

High Performance ZrNbAl Alloy with Low Thermal Expansion Coefficient

Thermal expansion is a common phenomenon in both metals and alloys, which is important for metallic material applications in modern industry, especially in nuclear and aerospace industries. A lower thermal expansion coefficient may cause lower thermal stress and higher accuracy. A new Zr-based alloy is developed and presented.The XRD diffraction results demonstrate that only a close-packed hexagonal phase（α or α＇ phase） exists in the microstructure. The thermal expansion and mechanical properties are studied. According to the experimental results, the new Zr-based alloy presents a low thermal expansion coefficient and good mechanical properties.Also,its thermal expansion coefficient is stable through solution treatment.

Low thermal expansion and broad band photoluminescence of Zr0.1Al1.9Mo2.9V0.1O12

A new material of Zr0.1Al1.9Mo2.9V0.1O12 is synthesized by the traditional solid state synthesis method.The phase transition,coefficient of thermal expansion,and luminescence properties of Zr0.1Al1.9Mo2.9V0.1O12 are explored with Raman spectrometer,dilatometer,and x-ray diffraction(XRD)diffractometer.The results show that the Zr0.1Al1.9Mo2.9V0.1O12 possesses the strong broad-band luminescence characteristics almost in the whole visible region.The sample is crystallized in a monoclinic structure group of P21/a(No.14)crystallized at room temperature(RT).The crystal is changed from monoclinic to orthorhombic structure when the temperature increases to 463 K.The material has very low thermal expansion performance in a wide temperature range.Its excellent low thermal expansion and strong pale green light properties in a wide temperature range suggest its potential applications in light-emitting diode(LED)and other optoelectronic devices.

Development and Application of Zero Expansion Silica Brick for Hot Repairing of Coke Oven

In order to meet the needs of hot repairing technology of coke oven, the zero expansion, silica brick with super properties has been developed, and the problem of poor thermal stability of common silica brick has been over-comed . This product can be directly used after being rapidly heated after construction. At present, it has been applied in coke ovens in Italy and Baosteel.

Effects of Al particles and thin layer on thermal expansion and conductivity of Al-Y_2Mo_3O_(12) cermets

Low thermal expansion composites are difficult to obtain by using Al with larger positive thermal expansion coefficient（TEC） and the materials with smaller negative TECs. In this investigation, Y2Mo3O12 with larger negative TEC is used to combine with Al to obtain a low thermal expansion composite with high conductivity. The TEC of Al is reduced by 19%for a ratio Al：Y2Mo3O12 of 0.3118. When the mass ratio of Al：Y2Mo3O12 increases to 2.0000, the conductivity of the composite increases so much that a transformation from capacitance to pure resistance appears. The results suggest that Y2Mo3O12 plays a dominant role in the composite for low content of Al（presenting isolate particles）, while the content of Al increases enough to contact each other, the composite presents mainly the property of Al. For the effect of high content Al, it is considered that Al is squeezed out of the cermets during the uniaxial pressure process to form a thin layer on the surface.

Effect of Solid Solution Treatment on Microstructure of Fe-Ni Based High Strength Low Thermal Expansion Alloy

The influence of solid solution treatments on the dissolution of carbides precipitates,the grain size,and the hardness of high strength low expansion alloy were investigated through XRD analysis,microstructure observations,and theoretical computation.It was seen that most primary Mo2C type carbide band dissolved in a temperature range of 1 100-1 150 ℃.When the temperature was over 1 200 ℃,the grain size increased remarkably,which led to the reduction of hardness.

Effect of Na_(2)O Content on the Structure and Properties of LAS Glass-ceramics Prepared by Spodumene

The Li_(2)O-Al_(2)O_(3)-SiO_(2) (LAS) glass-ceramics with low lithium content were prepared from spodumene mineral by melting method.XRD,DSC,and FTIR were used to study the crystallization process and structure of the samples.The results showed that the addition of Na_(2)O promoted the precipitation of β-quartz solid solution and its transformation to β-spodumene solid solution.Mechanical performance tests and FESEM indicated that the larger grain size and inhomogeneous grain dispersion caused by the increase of Na_(2)O content led to lower mechanical properties.In addition,low expansion glass-ceramics were prepared by an appropriate heat treatment according to DSC result,and when Na_(2)O content was in the range of 1.22 wt% to 2.41 wt%,the average coefficient of thermal expansion (CTE) (30-300 ℃) increased from-5.810 ×10^(-7 )to 5.322×10^(-7)℃^(-1).