Performance of water-based foams affected by chemical inhibitors to retard spontaneous combustion of coal

The micelle generating process of the sodium dodecyl sulfate(SDS) solution with the addition of chemical inhibitors was elucidated using phase separation model, and the descending order of the capacity for the selected chemical inhibitors to reduce the critical micelle concentrations of the solution are Mg Cl_2, Ca Cl_2,NH_4HCO_3 and NH_4Cl. The data to quantitatively describe the foam decay process, including foaming ratio,foam life and decay behaviors, was obtained by pressure measuring system. The results indicate that chemical inhibitors can improve the solution foamability. The capacity of the inhibitors to enhance the solution foamability is sorted as NH_4 Cl, NH_4HCO_3, Mg Cl2 and Ca Cl_2 which can distinctly improve the foam stability as well. The capacity of the inhibitors to enhance the SDS foam stability can be arranged as Mg Cl_2, NH_4 Cl, NH_4HCO_3 and Ca Cl_2. It is observed that the gravity drainage plays a leading role in the increase of proportion of diffusion drainage. The oxidation dynamic parameters of the coal samples treated by inhibition foams were investigated using thermal analysis technique, and their synergistic effects on inhibiting coal oxidation were explored.

Optimization of pore structure and wet tribological properties of paper-based friction materials using chemical foaming technology

Paper-based friction materials are porous materials that exhibit anisotropy;they exhibit random pore sizes and quantities during their preparation,thereby rendering the control of their pore structure difficult.Composites with different pore structures are obtained by introducing chemical foaming technology during their preparation to regulate their pore structure and investigate the effect of pore structure on the properties of paper-based friction materials.The results indicate that the skeleton density,total pore area,average pore diameter,and porosity of the materials increase after chemical foaming treatment,showing a more open pore structure.The addition of an organic chemical foaming agent improves the curing degree of the matrix significantly.Consequently,the thermal stability of the materials improves significantly,and the hardness and elastic modulus of the matrix increase by 73.7%and 49.4%,respectively.The dynamic friction coefficient increases and the wear rate is reduced considerably after optimizing the pore structure.The wear rate,in particular,decreases by 47.7%from 2.83×10^(−8) to 1.48×10^(−8)cm^(3)/J as the foaming agent content increases.Most importantly,this study provides an effective method to regulate the pore structure of wet friction materials,which is conducive to achieving the desired tribological properties.