油溶性钙掺杂氟化镧纳米粒子的制备及其摩擦性能研究

Study on Preparation of Oil-soluble Calcium-doped LaF_3 Nano-particles and Its Tribological Properties

在乙醇-水体系中,以二辛基二硫代磷酸双(β-)羟乙基十八胺盐为表面修饰剂,以氯化钙和氯化镧为原料,制备了油溶性钙掺杂氟化镧纳米粒子和氟化镧与氟化钙混合体纳米粒子。通过X射线衍射仪(XRD)、透射电镜(TEM)、热重仪(TG)及傅立叶红外(FTIR)表征了表面修饰纳米粒子的结构及形貌,利用离心沉降法和升温法结合研究了添加剂中纳米粒子在500SN基础油中的分散稳定性和高温稳定性,利用四球机考察了纳米粒子的摩擦学性能,并通过SEM分析了钢球磨斑表面。结果表明:La、Ca摩尔比为1∶1时,纳米粒子为氟化镧晶体和氟化钙晶体的混合物;La、Ca摩尔比为1∶2时,其结构为掺杂体;2种纳米粒子形貌和粒径一样,平均粒径在10nm左右;在500SN基础油中具有良好的分散稳定性;掺杂体纳米粒子的摩擦学性能高于混合体纳米粒子,含掺杂体纳米粒子油样的最大无卡咬负荷值比基础油提高了1.15倍,磨斑直径比基础油降低了42.6%。

Oil-soluble cacium-doped LaF3 nano-particles and LaF3 and CaF2 mixed nano-particles were prepared in a mixture solution of water-ethanol with dioctyl dithiophosphoric acid di （β-ethoxyl） stearamine as a surface modifier, and calcium chloride and lanthanum chloride as reactants. Morphology and structures of surface modification nano-particles were characterized by XRD, TEM , FFIR and TG. Dispersing stability and high temperature stabi!ity of nano-partieles in 500 SN base oil were measured respectively by a centrifugal setting method and a temperature-increasing method. Tribological properties of nano-particles were investigated by a four-ball machine. Wear scars of steel balls were investigated by SEM. Results show that nano-particles are the mixture of LaF3 and CaF： crystals when the molar ratio of La and Ca is 1 ： 1 ; the crystalline phases of the nano-particles are dopant structures when the molar ratio of La and Ca is 1：2;morphology and particle diameter of the two nano-particles are the same, and the average diameter is about 10 urn;the two nano-particles have good dispersing stability and high temperature stability in 500SN base oil;the tribological properties of the dopant nano-particles are higher than that of the mixture nano-particles, compared with 500SN base oil, the maximum non-seizer load value of the oil sample with the dopant nano-particles is increased by 1.15 times, and the wear scar diameter is decreased by 42. 6%.