Micro-tribology for advanced magnetic storage system

为了改善在接触或近接触记录条件下工作的磁头/硬盘界面的摩擦学性能，进行了几项研究。(1)利用离子束辅助沉积(IBAD)技术，在单晶硅和1.8英寸磁性硬盘上成功地制备了厚度为1.5-100 nm的新型氮化碳保护膜。对沉积的C-N涂层的摩擦学性能进行了测试，并与工业碳涂层在相同磁介质上的性能进行了比较，结果表明：(A)C-N涂层与氮化硅销钉摩擦时的摩擦系数在0.10-0.12之间。这一摩擦系数低于碳涂层(约0.3)。(B)氮化碳涂层的寿命是碳涂层的5倍左右。(2)沉积参数对碳氮涂层…的影响研究了材料的粗糙度、硬度、残余应力、摩擦学寿命和摩擦系数等性能。发现残余应力对涂层摩擦学寿命的影响最大。(3)将碳化硅和氧化铝两种不同的陶瓷与涂有商品碳涂层的磁性硬盘进行了对比试验。结果表明：(1)碳化硅滑块比氧化铝滑块具有更长的使用寿命。涂层寿命短的主要原因是由于形成的锋利边缘造成碳涂层的严重磨损，导致氧化铝滑块表面的颗粒脱落。(2)碳涂层的失效主要是由于机械磨损引起的低速滑动。然而，在高速下，高摩擦产生的温度是涂层失效的主要原因。提出了一种当整个磨损过程都集中在表面粗糙处时的磨损量和比磨损率的计算方法(以带1.5-35 nm薄保护层的织构磁盘为例)。该方法使用初始表面和磨损表面的轴承曲线来估计磨损量。用该方法评价了磁性硬盘上薄碳和氮化碳涂层的比磨损率。C-N涂层圆盘的比磨损率约为10-5，比同厚度商品碳涂层的磨损率低约10倍。较少

In order to improve a tribological performance of the magnetic head/rigid disk interface operating under conditions of contact or near-contact recording, several studies were carried out. The obtained results may be summerized as follows :(1) A new type of protective carbon nitride (C-N) coating, 1.5-100 nm thick, was successfully synthesized by means of ion beam assisted deposition (IBAD) on both single-crystalline silicon and on the magnetic media of 1.8" magnetic rigid disk. Testing of tribological properties of the deposited C-N coating and their comparison with properties of the commercial carbon coating on the same magnetic media have shown, that :(a) friction coefficient in the range of 0.10-0.12 was observed for C-N coating sliding against silicon nitride pin. This friction coefficient was lower than that of carbon coating (about 0.3).(b) carbon nitride coating provided about five times longer life than carbon coating.(2) The effect of deposition parameters on such C-N coating … More properties as roughness, hardness, residual stress, tribological life, and the coefficient of friction was studied. It was found, that the residual stress has the strongest effect on the coating tribological life.(3) Two different ceramics such as SiC and Al203 were tested against a magnetic rigid disk coated with a commercial carbon coating. It was shown, that :(a) Silicon carbide slider provided much longer life of unlubricated disk than slider made of alumina. Grain detachment from alumina slider surface followed b severe abrasion of the carbon coating by formed sharp edges was found to be the main reason of short coating life.(b) Failure of carbon coating, sliding at low velocity against ceramic slider, occurred mainly bacause of mechanical wear. At a high velocity, however, a high friction-generated temperature was mostly responsible for the coating failure. A model and an empirical equaion were suggested to predict a maximum coating life at high sliding velocity using the calculated flash temperature value.(4) A method of the wear volume and the specific wear rate calculatin for the case when the whole wear process is localized in the surface asperities (a case of the textured magnetic rigid disk with a thin 1.5-35 nm protective ovsrcoat) was suggested. The method uses a bearing curves of the initial and worn surfaces to estimate the worn volume. This method was used for the evaluation of the specific wear rate of thin carbon and carbon nitride coatings on the magnetic rigid disk. The specific wear rate for the C-N coated disk was estimated to be about 10-5, which is about ten times smaller than that of commercial carbon coating of the same thickness. Less