Optimum preparation technology for Chinese fir wood/Ca-montmorillonite (Ca-MMT) composite board

For this study, an intercalation compounding method was used to prepare Chinese fir wood/Ca-montmorillonite （Ca-MMT） composite board to improve its properties such as surface mechanical properties, flame retardance and dimensional stability. By virtue of water-soluble phenolic resin （PF）, Chinese fir wood and Ca-MMT were mixed by pressure and vacuum impregnation. The optimum impregnation technology of Chinese fir wood/Ca-MMT composite board was obtained by using an orthogonal design and a single factor design of pressure and vacuum impregnation, using weight percent gain （WPG） as the basic index. The results are as follows： 1） On the basis of the orthogonal design and an actual experiment, the optimum preparation technology of Chinese fir wood/Ca-MMT composite board is 20% PF resin dispersion concentration （wt%）, 1.0 CEC amount of organic intercalation agent, 0.098 MPa vacuum degree, 5% concentration of Ca-MMT and 1.0 MPa pressure. 2） The WPG of the composite board samples of 450 mm length was much larger than that of the samples of 600, 750 and 900 mm length. Warm water extraction contributed little to WPG

Experimental and numerical study regarding H-steel all-bolted connection steel frame with composite wall boards

H-steel all-bolted connection steel frame structures with heat preservation and decoration composite wall boards were investigated and the seismic performances of three scaled specimens were studied.The failure modes,hysteresis curves,bearing capacity,ductility,energy dissipation capacity,stiffness degradation and strain distribution were discussed.The calculation method of structural theoretical internal force was presented.The results showed that the overall structural seismic performance was better,and the structural ductility met the demands of elastic-plastic inter-story drift angle for seismic design.The H-steel weak-axis connection structure obtained better energy dissipation capacity,and its bearing capacity and stiffness were slightly different from the strong-axis connection.The heat preservation and decoration performance of composite wallboard and the all-bolted connection of the steel frame realized prefabrication during the whole construction period.The plastic hinge of the steel beam can be moved outwards because of the L-angles,which effectively avoids stress concentration in joint areas and expands the plastic hinge range.The errors between the theoretical structural capacity calculated by the plastic analysis method and the test results were within 2.44%.In addition,structural failure mechanisms and bearing capacities were verified by the finite element(FE)analysis,and the effects of the main parameters on the structures were investigated.The FE verification results were the same as in the test.The research results provide theoretical support and technical guidance for the application of thermal insulation and decorative composite wall panels in H-shaped steel all-bolted steel frames.

Experimental Study on Corrosion of Stainless Steel in Low Temperature Multi effect Seawater Desalination

Starting from the corrosion mechanism,this paper analyzes the characteristics of various types of stainless steel and selects the best performance composite plate composite plate stainless steel.Analyze and select the most suitable corrosion detection method based on specific practical multi working conditions,discuss the interference factors that affect metal corrosion during experimental simulation,and the advantages of newly developed sheet metal.The new development of composite board panels,with the substrate and composite materials applying their respective capabilities for MED,will bring breakthrough progress to the scientific research and engineering applica-tion of composite boards.

Effects of wollastonite nanofibers on fluid flow in medium-density fiberboard

We studied the effect of wollastonite nanofibers on fluid flow in medium-density fiberboard （MDF）. Nanowollastonite （NW） was applied in MDF at 10 %, based on the dry weight of wood fibers. We also tested chicken feathers as an additive to the matrix at 5 and 10 % by weight. The weight of feathers was reduced from the wood fibers to keep the density of the panels constant （0.66 g cm-3）. Wollastonite nanofibers acted as filler in the matrix and significantly decreased gas and liquid perme- ability. Higher thermal conductivity of the N-W-treated MDF-mats resulted in a better cure of resin, and conse- quently more integrity in the composite-matrix and lower permeability. The water-repellant property of wollastonite also contributed to the decrease in liquid permeability. Feathers reduced gas and liquid permeability due to the hydrophobic nature of keratin, as well as its formation as a physical barrier towards passing of fluids. Ten percent feather content proved too high and some checks and cracks occurred in the core of the panels after hot-pressing. Panels with 5 %-feather content resulted in both lower fluid flow and adequate physical integrity in the core sec- tion of the MDF-matrix.