核—壳包覆自润滑陶瓷刀具研制及其切削性能研究

发布时间：2018-04-12 20:00

本文选题：表面包覆 + CaF_2@Al_2O_3　；参考：《山东大学》2016年博士论文

【摘要】：本文面向干切削加工刀具应用领域,提出将颗粒表面包覆改性的材料设计思想引入自润滑陶瓷刀具设计领域,设计制备了既具有自润滑能力又具有较好力学性能的核-壳包覆自润滑陶瓷刀具,实现了刀具材料力学性能与润滑性的统一。应用非均匀成核理论,研究了核-壳型CaF_2@Al(OH)3包覆微粒的形成机理,分析了Al(OH)3晶体在CaF_2颗粒表面稳定成核和生长的机理和条件；确定了过饱和度AC为Al(OH)3的析晶推动力,AC越大越有利于CaF_2@Al(OH)3包覆微粒的形成和生长。使用Material Studio软件模拟了CaF_2@Al(OH)3包覆微粒的形成过程,模拟结果显示A1(OH)3分子能够在CaF_2颗粒表面稳定成核,与试验结果吻合。采用非均匀成核法制备了CaF_2@Al203核-壳包覆微粒,采用XRD、IR光谱、SEM、TEM等测试方法,对最优条件下制备的核-壳包覆微粒进行了表征和分析,确定了包覆微粒的结构和形貌。试验研究了工艺参数对CaF_2@Al(OH)3包覆微粒形态和包覆率的影响,确定了最优工艺参数为pH值为7.5,A13+浓度为0.15 mol/L,温度T为75℃,氨水滴定速度为3mL/min,此时包覆微粒的包覆率最高,包覆效果最好。分别以Al_2O_3/TiC和Al_2O_3/Ti(C,N)为基体,制备了不同CaF_2@Al203含量的核-壳包覆自润滑陶瓷刀具材料。当CaF_2@Al203含量为10 vo1.%时,Al_2O_3/TiC/CaF_2@Al203刀具材料综合力学性能最好,其抗弯强度为662 MPa,断裂韧性为6.34 MPa.m1/2,硬度为16.86 GPa。与添加相应含量CaF_2的刀具材料相比,其性能分别提高19.06%,36.93%和12.25%。当CaF_2@Al203含量为10 vo1.%时,Al_2O_3/Ti(C,N)/CaF_2@Al_2O_3刀具材料综合力学性能最好,其抗弯强度为680MPa,断裂韧性为6.50 MPa-m1/2,硬度为17.29 GPa,。与相应含量添加CaF_2的刀具材料相比,以上性能分别提高12.21%,29.48%,14.50%。材料表面和断口显微结构分析表明,CaF_2@Al203核-壳结构是刀具材料力学性能改善的主要原因。添加CaF_2@Al203的核-壳包覆自润滑陶瓷刀具材料的增强机理为CaF_2@Al203核-壳结构在烧结过程中能够防止CaF_2熔融后扩散,增强刀具材料的致密化程度：能够诱发穿晶断裂,抑制Al_2O_3晶粒长大,阻止裂纹扩展,起到细化晶粒的作用,使刀具材料的力学性能和润滑性能得到统一。研究了CaF_2@Al_2O_3含量对AT-C@X系列和ATCN-C@X系列刀具材料摩擦磨损特性的影响。试验表明,刀具材料的摩擦系数随CaF_2@Al_2O_3含量增加而减小,磨损率随CaF_2@Al_2O_3含量的增加先减小后增大。研究了试验条件对AT-C@X系列和ATCN-C@X系列刀具材料摩擦磨损特性的影响。试验表明,刀具材料的摩擦系数随载荷的增大而降低,磨损率随载荷的增大而升高；摩擦系数和磨损率均随滑动速度的增大而下降。相同试验条件下,添加CaF_2@Al_2O_3的刀具材料的减摩性能与对应只添加CaF_2的自润滑陶瓷刀具材料相当,耐磨性能高于相应只添加CaF_2的自润滑陶瓷刀具材料。研究了CaF_2@Al_2O_3含量对AT-C@X系列和ATCN-C@X系列刀具切削40Cr淬火钢的切削性能的影响。研究表明,在刀具中添加CaF_2@Al_2O_3具有良好的减摩效果,可以降低切削力和切削温度,改善加工工件的表面粗糙度,但由于硬度降低,刀具后刀面磨损量略大。添加CaF_2@Al_2O_3的AT-C@X系列刀具的后刀面磨损量分别随切削速度、背吃刀量和进给量的增加而明显增加,而加工工件的表面粗糙度分别随切削速度、背吃刀量和进给量的增加而缓慢升高,说明AT-C@X系列刀具具有良好的切削性能。AT-C@10刀具的前刀面磨损包括微崩刃、月牙洼磨损以及粘结磨损,后刀面磨损包括粘着磨损、磨粒和边界磨损；ATCN-C@10刀具的前刀面也存在轻微的月牙洼磨损和粘结磨损,后刀面为磨粒磨损、粘着磨损和边界磨损。AT-C@10刀具的切屑呈连续带状,ATCN-C@10刀具加工的切屑为带状和锯齿状。ATCN-C@10刀具加工的切屑的氧化明显高于AT-C@10刀具。
[Abstract]:The dry cutting tool applications, the material design idea of modified particles coated on the surface of the field of introduction of self lubricating ceramic cutting tool design, designed and fabricated with core-shell self-lubricating ability and good mechanical properties of the coated Self-lubricating Ceramic Tool, realizes the unified performance and lubricating tool material mechanics application of heterogeneous nucleation theory of core-shell type CaF_2@Al (OH) 3 coating particles formation mechanism, analysis of the Al (OH) 3 crystals into the mechanism and conditions of nucleation and growth in the stable surface of CaF_2 particles; the supersaturation degree of AC Al (OH) crystallization driving force of the 3. AC is more conducive to the growth of 3 and CaF_2@Al (OH) formed with coated particles. The simulation using the CaF_2@Al Material software Studio (OH) 3 particles coated by the forming process, the simulation results show that the A1 (OH) 3 molecules on the surface of CaF_2 particles and stable nucleation, and the test results Well. By heterogeneous nucleation prepared CaF_2@Al203 core-shell particles coated with XRD, SEM, TEM, IR spectra, test methods, the optimal conditions for the preparation of core-shell coated particles were characterized and analyzed to determine the structure and morphology of coated particles. Experimental study on process parameters CaF_2@Al (OH) 3 coated particle morphology and encapsulation rate effects, determine the optimal parameters for the pH value is 7.5, the concentration of A13+ was 0.15 mol/L, the T temperature is 75 DEG C, ammonia titration rate is 3mL/min, the coated particles by coating the coating effect was the best. The highest rate, respectively by Al_2O_3/TiC and Al_2O_3/Ti (C, N) as matrix and preparation of core-shell coating with different content of CaF_2@Al203 self-lubricating ceramic tool material. When the content of CaF_2@Al203 is 10 vo1.%, the mechanical performance of the best Al_2O_3/TiC/CaF_2@Al203 tool material, the flexural strength is 662 MPa, the fracture toughness of 6.34 MPa.m1/2, The hardness is 16.86 GPa. compared with the tool material add the corresponding content of CaF_2, its properties were increased by 19.06%, 36.93% and 12.25%. when the CaF_2@Al203 content is 10 vo1.%, Al_2O_3/Ti (C, N) /CaF_2@Al_2O_3 comprehensive mechanical performance is the best tool material, the bending strength is 680MPa, the fracture toughness is 6.50 MPa-m1/2, hardness is 17.29 GPa. Compared with the corresponding content adding tool material CaF_2, the above properties were increased by 12.21%, 29.48%, 14.50%. analysis showed that the material surface and microstructure, CaF_2@Al203 core-shell structure is the main reason of the tool material mechanical properties improvement. The core-shell added CaF_2@Al203 coating self reinforcement mechanism of lubricating ceramic cutting tool material for CaF_2@Al203 core shell the structure can prevent the CaF_2 melting diffusion in the sintering process, enhance densification of tool materials: can induce transgranular fracture, inhibition of Al_2O_3 grain growth, prevent Crack propagation, play a role in grain refinement, mechanical properties and lubricating properties of tool materials are unified. The effects of CaF_2@Al_2O_3 content on friction and wear characteristics of AT-C@X series and ATCN-C@X series tool materials. The results show that the friction coefficient of tool material decreases with the increase of CaF_2@ Al_2O_3 content, the wear rate increases with increasing CaF_2@Al_2O_3 content in the first decreases. Study the test conditions of friction and wear characteristics of AT-C@X series and ATCN-C@X series tool materials. The results show that the friction coefficient of tool material decreases with the increase of the load, the wear rate increases as the load increases; the friction coefficient and the wear rate increases with sliding velocity decreased. Under the same experimental conditions the addition of CaF_2@Al_2O_3 tool material, reducing friction properties of self-lubricating material and corresponding only adding CaF_2 is higher than the phase resistance Self-lubricating ceramic tool material should only add CaF_2. To study the effects of CaF_2@Al_2O_3 content on the cutting performance of AT-C@X series and ATCN-C@X series of cutting hardened steel 40Cr. The results show that the addition of CaF_2@Al_2O_3 in the tool has good anti friction effect, can reduce the cutting force and cutting temperature, improve the surface roughness of the workpiece, but because the hardness decreased, the tool flank wear slightly. After adding CaF_2@Al_2O_3 AT-C@X series cutter knife surface of the wear rate increased with the cutting speed, depth of cut and feed and increased significantly, and the work piece surface roughness respectively with the cutting speed, increase the depth of cut and feed and increased slowly, including micro chipping wear surface before the knife AT-C@X series tool has good cutting performance of.AT-C@10 tool, crater wear and adhesive wear, flank wear including Adhesive wear, abrasive wear and boundary wear; the rake face of ATCN-C@10 tool are crater wear and slight adhesive wear, flank abrasive wear, adhesive wear and cutting tool wear.AT-C@10 boundary is continuous strip, ATCN-C@10 oxidation chip cutter for strip and jagged.ATCN-C@10 cutter the chip was significantly higher than that of the AT-C@10 tools.

【学位授予单位】：山东大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TG711

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