Xin Gang Yu

Pore Structure and Microstructure of Foam Concrete

The pore structure and microstructure of the foam concrete was analyzed by scanning electron microscopy and light microscopy combined with digital image analysis. The results show that: (1) even-distributed fine and close pores resulting in high strength and low permeability; (2) uneven-distributed large size pores and open pores lead to low strength and high permeability; (3) light microscopy combined with digital image analysis is a cheap and convenient tool fitting for the pore structure analysis of the foam concrete; (4) scanning electron microscopy is very appropriate for the pore structure and microstructure analysis of the foam concrete.

Study on the High Performance Coal Gangue Foam Concrete

The high performance coal gangue foam concrete with the dry density less than 440kg/m3, the thermal conductivity less than 0.085W/(m•K) and the compressive strength over 2.0 MPa was prepared. The microstructure of the coal gangue foam concrete was analyzed by SEM. The hydrates of the coal gangue foam concrete were detected by XRD, and the temperature stability of the coal gangue foam concrete was analyzed by DTA and DSC.

Microstructure, Mineral Phases and Strength of the Foam Concrete

The relationship among the composition, microstructure and strength of materials is always one of the hotspots for scholars of materials research. The influence of curing time on the compressive strength and flexural strength of the foam concrete with the cement, cement-slag and cement-steel slag as main binder respectively was studied in this paper. The microstructure of these foam concrete was analyzed by SEM and the mineral phases of the foam concrete was analyzed by XRD. The relationship among the binders, microstructure, mineral phases and strength of the foam concrete were explored and the reasons of why the strength of the cement foam concrete and cement-slag foam concrete is much higher than that of the cement-steel slag foam concrete are proposed.

AFM Investigation of Nano Particle Incorporated Sb Doped SnO2 Films

Antimony doped tin oxide (ATO) thin films were deposited onto silica coated soda lime silicate substrate by the sol-gel method using Sb(OC4H9)4 and Sn(OC4H9)4 as the precursor materials. Conductive tin oxide nano particles of different particle size were added into the sols. The films were subjected to heat treatment at t=500) for about one hour. Film structure and surface morphology has been investigated by means of atomic force microscopy (AFM). Room temperature electrical resistivity of the films was measured using the conventional four probe van der paul method. The influence of incorporation of conductive nano particles on the electrical conductivity of Sb-doped tin oxide films was studied. The correlation between the microstructure and the film electrical property has been obtained. The status of the nano particles in the films has also investigated by FTIR spectroscopy.

Macro-Residual Stress in 304 Stainless Steel Coated with ZrO2-CeO2 Thin Films by Sol-Gel Process

X-ray diffraction (XRD) method to measure the residual stress existing in the metal substrate surface layer was introduced and the sol-gel ZrO2-CeO2 thin film was successfully prepared on SUS304 stainless steel substrate by dip-coating process. The macro residual stress existing in metal substrate was analyzed by XRD. It turns out that the compressive stress existing in the metal substrate surface layer increases with the increase of heat-treated temperature. Based on the above study, colored stainless steels of high quality were prepared by sol-gel process.

Pore Structure and Microstructure of Super Light-Weight Foam Concrete Reinforced by Inorganic Fiber

Super light-weight foam concrete with the density less than 250Kg/m3 was prepared by the physical foaming method. The pore structure and microstructure of the super light-weight foam concrete was analyzed by scanning electron microscopy.

Preparation and Performance Characterization of Active Coal Gangue Powder (ACGP) Used for Cement Admixture

Two kinds of high active coal gangue powder (ACGP) were prepared by heat treated and ball milled coal gangue. The density, fineness, Loss on ignition (LOI), activity and influence of the fineness of the two kinds of ACGP on the density and I/W (compressive strength to weight of the foam concrete specimens) of foam concrete were also studied in this paper. The results show that the density and I/W of the foam concrete were greatly affected by the fineness of ACGP. The finer of the ACGP, the lower density and higher I/W of the coal gangue foam concrete will be got. Based on the experimental results, a method to evaluate the activity of active powder used for cement admixture is proposed and the activity of the ACGP is also evaluated.

Effect of Fly Ash Content on Properties of Fly Ash-Coal Gangue Foam Concrete

The effect of the fly ash content on the properties of the fly ash-coal gangue foam concrete was studied in this paper. Results revealed that: With the increase of the fly ash content, the dry density, the compressive strength and the shrinkage of the fly ash-coal gangue foam concrete decrease; the density of the fly ash - coal gangue foam concrete was influenced greatly by the ratio of water to total dry material. The pore structure and microstructure of the foam concrete was analyzed by scanning electron microscopy, and the results show that most of the pores are fine, closed, and even distributed.

Influence of Foaming Agent on the Properties of High Density Foam Concrete

Lightweight concrete has been used for structural purposes for many years and it is developed very fast in resent years due to its lightweight and favourable for insulation properties. High strength foam concrete is a fairly new kind of lightweight concrete with excellent properties of outstanding workability, low density and high strength. Responsible for these properties are the macro-, meso- and micro- porosity of the foam concrete which are mainly affected by the foaming agent. The influence of foaming agent’s dilution ratio and foam dosage on the fluidity, compressive strength, flexural strength and drying shrinkage of high density foam concrete designed for structural materials is investigated in this paper.

XPS Studies on Light-Yellow Glass Prepared by Sol-Gel Dip-Coating

Light-yellow glass was prepared by coating silver film on the flat glass substrate surface with sol-gel dip-coating process. The chemical composition and the valence state of elements on the surface of silver thin film deposited on glass substrate were studied by X-ray photoelectron spectroscopy. Results show that: elements of Na, Mg, Ca exist in the form of their respective stable state, such as Na2O, MgO, CaO, when heat treated at 500°C for 0.5h; but Si is unstable, and exhibit stoichiometrical disturbances. Results of chemical composition and their content by weight percent of silver thin film surface reveal that minute of quantity silver on the glass surface can lead to the glass with light-yellow color. The transmission of light for the light-yellow glass, deep-yellow glass and the flat glass substrate was also analyzed by spectrophotometer, and the results indicate that the light-yellow glass is capable of absorbing UV rays heavily.