大气等离子喷涂制备锰钴尖晶石涂层及其电导率

采用大气等离子喷涂(APS)工艺制备了Mn-Co尖晶石涂层,同时研究了不同载气和喷距对涂层形貌及电导率的影响.采用直流四电极法测量涂层的电导率,利用SEM,XRD和XPS等表征手段对涂层微观形貌、组成等进行表征.结果表明,所制备的涂层致密、孔洞较少、与基体结合良好,表面呈现液态沉积与微熔颗粒堆积相混合的状态.800℃时,载气量为2 SLPM下涂层的电导率是18 S/cm,而其余载气量下涂层电导率仅有8 S/cm,低载气量制备的Mn-Co涂层具有良好的导电性;800℃下只有喷距为130 mm的涂层电导率超过了10 S/cm,增加喷距对电导率影响较小,各涂层电导率分布较为接近.测试态涂层表面形成了各种取向的金字塔状尖晶石晶体结构,其尖晶石相衍射峰强度显著提高;高电导率涂层中2价和3价元素比例更接近1∶2,为典型的尖晶石结构,其表现出较高的电导率.因此,适当的载气流量和喷涂距离可使涂层中含有更多的高电导率尖晶石相.

Preparation of manganese-cobalt spinel coating and its electrical conductivity by atmospheric plasma spraying

The Mn-Co spinel coatings was prepared by atmospheric plasma spraying (APS) process, and the effects of different carrier gases and spray distances on the morphology and conductivity of the coatings were studied. The electrical conductivity of the coating was measured by the direct current four-electrode method, and the micro morphology and composition of the coating were characterized by SEM, XRD, XPS and other characterization methods. The results show that the prepared coating is dense, has fewer holes, and is well bonded to the substrate, and the surface is in a state of mixing liquid deposition and micro-melting particles accumulation. At 800°C, the conductivity of the coating under 2 SLPM is 18 S/cm, while the conductivity of the coating under the other carrier gas is only 8 S/cm. The Mn-Co coating prepared with low carrier gas has good conductivity; At 800°C, only the conductivity of the coating with a spray distance of 130 mm exceeds 10 S/cm. Increasing the spray distance has little effect on the conductivity, and the conductivity distribution of each coating is closer. Pyramid-shaped spinel crystal structures of various orientations are formed on the surface of the tested coating, and the intensity of the spinel phase diffraction peak is significantly improved. The peaks in the high-conductivity coating are stronger and sharper; the ratio of divalent and trivalent elements in the high-conductivity coating is closer to 1:2, which is a typical spinel structure and shows higher conductivity. Therefore, increasing the carrier gas flow and appropriately increasing the spraying distance can make the coating more layers are deposited in the molten state.