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采用无压烧结技术制备了软锰矿掺杂的高强度氧化铝质压裂支撑剂。通过X射线衍射、压汞式孔隙分析、扫描电子显微镜和筒压法分别研究了由软锰矿引入的MnO2和Fe2O3对支撑剂物相组成、孔结构、晶粒尺寸和抗破碎能力的影响。结果表明:当软锰矿掺杂量为0～5%(质量分数,下同)时,烧结样品中包括氧化铝、莫来石和钛酸铝相,软锰矿的掺入未明显改变晶体结构;当软锰矿掺量为5%时,Fe3+取代Al3+与组分中的TiO2反应并形成固溶体,MnO2固溶于Al2O3晶粒中,促进了Al2O3晶粒生长,过剩的Fe2O3和MnO2存在于陶瓷晶界处并在高温煅烧下形成液相促进致密化烧结;未掺杂样品中存在大量连通气孔,显气孔率为14.79%;掺入5%软锰矿后,显气孔率降低至5.29%,样品内部多为均匀分布的近球形闭气孔;在52MPa压力条件下,5%软锰矿掺杂样品的破碎率与未掺杂样品相比减少80.95%,抗破碎能力显著提高。
The soft manganese-doped high-strength alumina fracturing proppant was prepared by pressureless sintering technique. The effects of MnO2 and Fe2O3 introduced by pyrolusite on phase composition, pore structure, grain size and crush resistance of proppant were investigated by X-ray diffraction, mercury intrusion porosimetry, scanning electron microscopy and cylinder pressure method. The results show that when the content of pyrolusite is 0-5% (mass fraction, the same below), the sintered samples include alumina, mullite and aluminum titanate phases. The incorporation of pyrolusite does not change the crystal structure obviously. When the content of pyrolusite is 5%, Fe3 + replaces Al3 + with the TiO2 in the composition and forms a solid solution, and MnO2 dissolves in the Al2O3 grains to promote the growth of Al2O3 grains. Excess Fe2O3 and MnO2 exist at the grain boundaries And calcined at a high temperature to form a liquid phase to promote densification sintering. In the undoped sample, there are a large number of interconnected pores with a porosity of 14.79%. After mixing 5% pyrolusite, the apparent porosity decreased to 5.29% Uniform distribution of nearly spherical closed pores; under 52MPa pressure conditions, 5% of the pyrolusite-doped samples of the crushing rate compared with the non-doped samples to reduce 80.95%, the crushing resistance was significantly improved.