Jingming Zhao

Densification characteristics of chromia/alumina castables by particle size distribution

The quality of the refractories applied on integrated gasification combined cycle should be a key factor that affects both the reliability and the economics of gasifier operation. To enhance the workability of chromia/alumina castables, three types of ultrafine alumina powder were added to improve the workability. Densification behavior of such castables in the presence of ultrafine alumina was assessed through the measurement of parameters like flow value, viscosity, bulk density, apparent porosity, and microstructure evaluation by an SEM study. Its proved that the specific surface area and particle size distribution of ultrafine powders in matrix parts greatly influence the densification behavior of these castables.

Strength Enhancement of Sludge Based Geopolymer by Si/Al Ratio Variation

To obtain a new type of construction material with lower CO2 emission and energy consumption, fly ash was used as the main components. Solution of NaOH/KOH and water glass were applied as alkaline activator. The amount of water glass and the ratio of alkaline/water glass were varied to adjust Si/Al ratio to reach an optimal value. The specimens were cured in air and oven, then their mechanical properties such as compressive strength and bending strength were measured and their microstructures were investigated.

Influence of Sintering Process on the Mechanical Properties of Dental Zirconia Ceramics

Densification and mechanical properties of dental zirconia ceramics were evaluated by different sintering methods. Y-TZP zirconia block was used in this study. Sintering were performed in electric heating furnace and microwave sintering furnace, and then experimented and analyzed on a change in densification according to the sintering time, a change in densification according to thickness, flexural strength and micro-structure of zirconia specimens. Microwave sintering was very effective in considerable mechanical properties such as flexural strength and bulk density was drastically increased than conventional electric heating method. It is also shown that microwave sintering was faster and more economical than common method to be present in qualities which equal or exceed. It will be important to seek the accurate sintering condition of dental zirconia by microwave sintering method and the continuous research is necessary for the study of relationship between sintering methods and mechanical properties.

Strength Enhancement of Bottom Ash-Based Concretes Using Metakaolin

To replace bottom ash for natural sand completely, the mix proportions of bottom ash in concrete was adjusted according to tab density and replacement ratio of Metakaolin/Cement were established. And then testing for slump, setting time, and compressive strength was conducted. According to test results, the compressive strength of concrete using the bottom ash was lower than that of concrete using natural sand (BAO concrete). But by adjusting the amount of bottom ash in concrete according tab density so that the fine aggregate proportions change 44% to 38%, the compressive strength of concrete using the bottom ash could even be higher than BAO concrete. And the chloric content of concrete using the bottom ash increased as the replacement ratio of bottom ash increased, but it is satisfied with the chloric content of fresh concrete 0.30 kg/m2 below (concrete standard specification regulation value).

Strength Enhancement of Bottom Ash-Based Polymer Concretes

To replace bottom ash for natural sand completely, the mix proportions of bottom ash in concrete was adjusted according to tab density and replacement ratio of polymeric resin/Potland cement(PC) were established. And then testing for slump, setting time, and compressive strength was conducted. According to test results, the compressive strength of concrete using the bottom ash was lower than that of concrete using natural sand (BA0 concrete). But by adjusting the amount of bottom ash in concrete according tab density so that the fine aggregate proportions change 44% to 38%, the compressive strength of concrete using the bottom ash could even be higher than BA0 concrete. And as the polymeric resin content of bottom ash concrete increased, strength would be increased drastically, but proper dispersant should be cooperated with polymeric resin cement with fine bottom ash powders.