【作者】 徐淑艳；

【导师】 马欣新；

【作者基本信息】 哈尔滨工业大学 ， 材料学， 2007， 博士

【摘要】 本文通过非平衡磁控溅射方法沉积了BCN薄膜,并系统地研究了不同条件沉积的BCN薄膜的成分、键结构、纳米力学性能和纳米摩擦磨损行为。通过研究得出了不同沉积条件对BCN薄膜结构和性能的影响规律,阐明了BCN薄膜的成膜、划伤和破裂机制。另外对典型工艺制备的BCN薄膜进行了真空和大气环境下退火,研究了薄膜的高温稳定性。采用X射线光电子能谱(XPS)和傅立叶变换红外光谱(FTIR)对薄膜的成分和键结构进行了研究,结果表明可以通过调节靶表面磁场状态、工作气体中NB2B分压使BCN薄膜中各种元素的成分达到连续可控。随薄膜中C含量由25at%不断下降至14at%,薄膜中类BCB3.4B的B-C键含量减少,类BB4BC的B-C键含量增加;引入到薄膜中的N首先与B结合形成B-N键,随N含量不断增加至稳定值以后,部分N会与C结合生成C=N键。研究还表明,薄膜结构除与薄膜成分有关以外,还与薄膜的沉积过程有关。随靶功率的增加,薄膜结构的无序程度增加;基体偏压有利于生成B-N键,当基体偏压达到-400V时,生成了spP3P杂化的B-N键;沉积温度增加使B-N键含量增加。本文测试了不同工艺沉积的BCN薄膜的纳米力学性能,结果表明薄膜的纳米力学性能与薄膜的无序程度、键结构的种类和数量密切相关。对于BCN薄膜而言,如果薄膜无序程度较低,并含有较多spP2P杂化的B-N、C=N键,则薄膜的力学性能较差;随着薄膜无序程度的增加和spP2P杂化键含量的减少,薄膜的力学性能提高;如果薄膜中的spP3P杂化的B-N键和B-C键含量增加,薄膜的力学性能则会进一步提高。本文制备的薄膜的纳米硬度和弹性模量分别位于0.3GPa～36GPa和15GPa～356GPa之间。本文对BCN薄膜的纳米摩擦磨损行为进行了系统地研究,得到了薄膜摩擦磨损特性与结构和力学性能之间的依赖关系。研究表明对于含N的BCN薄膜而言,力学性能增加有利于提高薄膜的耐磨性能;对于不含N的薄膜,虽然硬度很高,但耐磨性能却很差,所以提高薄膜力学性能和提高薄膜耐磨性之间并非完全一致。基于对薄膜摩擦磨损行为的研究,对本文制备的薄膜提出了三种不同类型的薄膜划伤机制和失效过程。具有高力学性能的不含N薄膜,临界载荷小,摩擦系数在0.3左右,在划痕载荷作用下易发生脆性破裂和剥落,随划痕载荷的增加表现出的划伤失效过程为:弹性变形→薄膜出现微小裂纹→薄膜分层、剥落→薄膜被划破;具有较高力学性能的含N的BCN薄膜,临界载荷增大,摩擦系数降至0.1以下,随划痕载荷的增加表现出的划伤失效过程为:完全弹性变形→弹性变形为主,出现少量塑性变形→表层薄膜剥落,薄膜被划破;具有低力学性能的含N的BCN薄膜,临界载荷小,摩擦系数增大至0.4以上,随划痕载荷的增加出现明显的犁沟。为研究BCN薄膜的高温稳定性,本文对典型工艺制备的BCN进行真空和空气退火试验。退火试验表明该BCN薄膜随退火温度增加其结构有序化程度增加、力学性能下降。该BCN薄膜具有很好的真空高温稳定性,退火温度升高到1000PoPC时薄膜仍未分解,且退火未显著降低其耐磨性;薄膜在大气中退火温度达到600PoPC后发生氧化分解。更多还原

【Abstract】 BCN films were deposited by unbalanced magnetron sputtering in this dissertation. The composition, bonding structures, nano-mechanical properties and nano-tribological properties of the BCN films deposited at different process parameters were studied systematically. The effect of process parameters on the structure and properties of the BCN films were obtained. The growth mechanism, scratch and crack mechanism of the BCN films were illuminated. Otherwise,annealing tests of typical BCN film were carried out in vacuum and atmosphere, and thermal stability of the film were studied.The composition and bonding structure of BCN films were studied by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR), and the results indicated that the composition of BCN films is controllable by adjusting the magnetic field of the target surface and NB2B partial pressure. The content of like BCB3.4B B-C bonding decreased and that of like BB4BC B-C bonding increased with the decreasing of the concentration of C from 25at% to 14at%. N was prior to bonding with B to form B-N bonding, and then bonded with C to form C=N bonding with the increasing of N to stable value in the films. Besides of the composition, the deposition process also affects the bonding structure of the films. The disordered degree of the films increased with the increasing of target power. The content of B-N bonding increased with the increasing of bias and spP3P B-N bonding appeared when the bias reached -400V. The content of B-N bonding increased with the increasing of the deposition temperature.Nano-mechanical properties of BCN films deposited at different deposition process parameters were tested, and the results indicated nano-mechanical properties were related with the disorder degree, type and number of bonding structures. The mechanical properties of BCN films with low disorder degree and more spP2 PB-N、C=N bonding were worst. The mechanical properties of BCN films increased with the increasing of the disorder degree and the decreasing of the spP2P bonding content. The mechanical properties of BCN films would be improved further with the increasing of the contents of spP3P B-N and B-C bonding. The nano-hardness and modulus of BCN films in the dissertation were in the range of 0.3GPa～36GPa and 15GPa～356GPa, respectively.The nano-tribological properties of BCN films were studied systematically in the dissertation, and the relation among tribological properties, structure and mechanical properties of BCN films was obtained. The results indicated the increasing of the nano-mechanical properties was in favor of the enhancement of the tribological properties of BCN films which contained N. Films with no N exhibited high mechanical properties, but the tribological properties is worse. That is to say the mechanical properties were not consistent absolutely with the tribological properties. Based on the studies of tribological properties, the scratch mechanism and crack process of three different types were proposed. For the film which contained no N and owned high mechanical properties, critical load is small and friction coefficient is about 0.3. Brittle break and peel off took place under the load, and the scratch and crack process with the increasing of the load was: elastic deformation→microcrack appeared in the films→delamination and peel off→crack. For the BCN films which contained N and owned better mechanical properties, critical load increased and friction coefficient was below 0.1. The scratch and crack process of films with the increasing of the load was: entirety elastic deformation→elastic deformation is dominant and plastic deformation is lesser→crack. For the BCN films which contained N and owned the worst mechanical properties, critical load decreased and friction coefficient increased over 0.4, and deep furrow appeared with the increasing of the load.In order to study the thermal stability of typical BCN film, annealing tests of the film were carried out in vacuum and air. The results indicated that the order degree increased, and the mechanical properties of the film decreased with the increasing of annealing temperatures. The film exhibited better vacuum thermal stability, and did not decompound when the annealing temperature rose to 1000PoPC. Otherwise, the tribological properties of the film annealing in vacuum did not decrease obviously. The film was oxidized and decompounded when the annealing temperature rose to 600PoPC in air.更多还原