为了探明瓦斯氛围下煤水固液接触机制，搭建了瓦斯氛围下煤水润湿角测试系统，测试了CZ（山西成庄矿无烟煤）及DW（陕西大湾矿烟煤）2种煤样在不同甲烷及氦气压力条件下的润湿角变化，结合煤表面形貌测试、低压CO₂吸附试验及XRD试验分析了瓦斯氛围下煤水接触角的变化规律。结果表明，随着气体压力的增加，煤润湿角逐渐增加，但在吸附性气体环境中，煤润湿角增加幅度更为明显，在0～2 MPa，CZ煤样的润湿角由72.99°增加到106.90°，从亲水性润湿过渡为中性润湿，最终转变为疏水性润湿，而DW煤样的润湿角由61.23°增加到85.14°，始终为亲水性润湿。分析认为，煤对甲烷的吸附能力是影响煤润湿角的主要原因。煤吸附甲烷后，在煤表面形成气膜，特别是在高压条件下，煤孔隙中的游离气体也会阻碍水对煤的润湿。而且吸附甲烷后，煤表面自由能降低，表面状态更加稳定，致使润湿性进一步减弱。气液竞争吸附也是影响煤水润湿性减弱的原因之一。进一步的，无烟煤的表面更加粗糙且具有更加发育的微孔结构，致使其具有较高的表面自由能，对甲烷的吸附能力更强，这是造成无烟煤在甲烷氛围下其润湿角变化更为明显的重要因素。此外，煤中矿物质可以影响煤的瓦斯吸附能力及表面润湿特性，也是影响含瓦斯煤润湿角的重要因素。

In order to reveal the solid liquid contact mechanism of coal and water in gas atmosphere, the wetting angles for two kinds of coal samples were tested under the different gas pressures with methane or helium by a solid liquid contact angle test system in gas atmosphere. Combining with the coal surface morphology test, low pressure CO₂ adsorption experiments and XRD experiments, the change laws of wetting angle in gas atmosphere were analyzed. Results showed that the wetting angle increases with the growing gas pressure. However, in the gas atmosphere with adsorptive gas, the increase of coal wetting angle is more obvious. The wetting angle of the CZ sample increases from 72.99°to 106.90° in the range from 0 MPa to 2 MPa, and the wettability changes from hydrophilic wetting to neutral wetting, and finally to hydrophobic wetting. The wetting angle of the DW sample increases from 61.23° to 85.14° in the range of 0-2 MPa, and the wettability keeps in the hydrophilic wetting. The adsorption capacity of coal to methane is the main reason affecting the wetting angle of coal. After coal adsorbs methane, a gas film is formed on the coal surface leading to the poor wettability. Especially under the high pressure conditions, the free gas in pore may reduce the contact for coal and water. Moreover, the free energy of coal surface decreases after coal adsorbs methane, making the surface is more stable and thus the poor wettability. In addition, the competition adsorption also reduces the wettability. Furthermore, the surface of anthracite is rougher and has a more developed microporous structure, resulting in higher surface free energy and stronger adsorption capacity, which makes a remarkable change of wetting angle for anthracite in methane atmosphere. Finally, the minerals in coal can affect the gas adsorption capacity and surface wetting characteristics of coal, and it is also an important factor affecting the wetting angle of gas bearing coal.

1 试验

   1.1 煤样制备

   1.2 瓦斯氛围下煤润湿角试验

   1.3 煤表面三维形貌分析

   1.4 低压CO2吸附试验

   1.5 XRD试验

2 试验结果与分析

   2.1 瓦斯氛围下煤水接触角试验结果分析

   2.2 煤表面三维形貌试验结果分析

   2.3 低压CO2吸附试验结果分析

   2.4 XRD试验结果分析

3 讨论

4 结论及建议