Evaluations of tribological characteristics of PFPE lubricants on DLC surfaces of magnetic disks
Evaluations of tribological characteristics of PFPE lubricants on DLC surfaces of magnetic disks
复制标题
DOI：
10.1007/s11249-006-9193-6
复制
发表时间：
2007-01
影响因子：
3.2
通讯作者：
Y. He;Y. Fujikawa;H. Zhang;K. Fukuzawa;Y. Mitsuya
中科院分区：
文献类型：
--
作者：
Y. He;Y. Fujikawa;H. Zhang;K. Fukuzawa;Y. Mitsuya
本文介绍了浸涂在覆盖有类金刚石碳 (DLC) 膜的磁盘上的全氟聚醚 (PFPE) 润滑剂膜的粘附力和摩擦力的测量结果。我们开发了一种定制的销盘式微型摩擦测试仪来执行摩擦学测量。附着力测试是通过在固定盘表面上下拉/拉起1.5毫米直径的玻璃球来进行的，摩擦测试是通过在旋转盘表面上滑动玻璃球来进行的，而不改变附着力测试中的头盘界面条件。在轻负载和缓慢滑动的条件下对不同种类的 2 纳米和 6 纳米厚的 PFPE 润滑剂（极性：Zdol4000 和 Zdol2000；非极性：Z03）进行了实验，以尽量减少对分子层状结构的干扰。发现随着膜厚度的增加，粘附力按 Z03 > Zdol2000 > Zdol4000（减小速率）的顺序减小，这与单层厚度的顺序紧密对应，然后饱和到几乎相同的计算值。对于2nm厚薄膜的摩擦力，Zdol2000与Zdol4000和Z03相比具有非常大的摩擦力，而Zdol4000比Z03稍大。 Zdol2000 的最大摩擦力表明，2 nm 厚的 Zdol2000 形成了一个单层，作为固定层。随着油膜厚度的增加，Zdol2000的摩擦力下降，表明额外的润滑剂分子充当了移动层，而Z03的摩擦力保持不变，为最低值。通过将负载力与摩擦力关系外推到负负载力区域，发现Z03的摩擦力在零净负载（负载力加粘附力）时趋于零，而Zdol2000和Zdol4000的摩擦力呈现有限值，表明形成了固定层，其表现出与粘合橡胶材料相似的特性。研究发现，去湿表面仅在滑动的第一阶段摩擦力剧烈变化，经过几次滑动后变得稳定。
This article presents measurements of adhesion and friction of perfluoropolyether (PFPE) lubricant films dip-coated on magnetic disks covered with diamond-like carbon (DLC) film. We have developed a custom-built pin-on-disk type micro-tribotester to perform the tribological measurements. The adhesion tests were performed by pulling down/up a 1.5-mm-diameter glass ball on a stationary disk surface, and the friction tests were carried out by sliding the glass ball on a rotating disk surface without changing head-disk interface conditions from the adhesion tests. Experiments were performed for the different kinds of 2- and 6-nm-thick PFPE lubricants (polar: Zdol4000 and Zdol2000; nonpolar: Z03) under lightly loaded and slow sliding conditions to minimize disturbance against the molecular layered structure. The adhesive forces were found to decrease with increasing film thickness in the order of Z03 > Zdol2000 > Zdol4000 (decreasing rate), which closely corresponds to the order of monolayer thickness, and then to saturate to almost the same calculated values. As for the friction forces of 2-nm-thick films, Zdol2000 featured extraordinarily large friction in comparison with Zdol4000 and Z03, while Zdol4000 was slightly larger than Z03. The largest friction of Zdol2000 reveals that the 2-nm-thick Zdol2000 formed a monolayer that served as an immobile layer. With the increase in film thickness, the friction force of Zdol2000 decreased, indicating that extra lubricant molecules served as a mobile layer, while that of Z03 remained unchanged as the lowest value. By extrapolating the loading force versus friction force relationship into a negative loading force region, it is found that the friction force of Z03 tended to zero at zero net load (loading force plus adhesion force), while those for Zdol2000 and Zdol4000 exhibited finite values, indicating formation of an immobile layer, which shows similar characteristics to those of adhesive rubber material. The dewetted surface is found to feature violently changing friction force only at the first stage of sliding, and it then becomes stable after several sliding passes.