Wear Characteristics of Carbon-Coated Magnetic Rigid Disks With Well-Defined Surface Texture

Wear characteristics are described for carbon-coated magnetic rigid disks with well-defined surface textures. Concentric circular hills with uniform height (ca. 80 nm) are produced on a disk surface using a photo-lithography technique, to control the apparent area of contact with a slider. Wear depth on the order of nanometers of the carbon overcoat is evaluated from the decrease in hill height after a drag test. Wear depth increases proportionally with the increase in average contact pressure, which is calculated from the load and apparent area of contact between the disk and slider. Lubricant diminishes wear of the carbon overcoat approximately 50 percent compared with that of an unlubricated overcoat.

Frictional Characteristics of Apparel Fabrics

A study has been conducted to determine the frictional characteristics of several fabrics used in apparel. The objective was to generate fabric frictional data to help in developing automated assemblies for fabrics. The results revealed that the coefficients of static and dynamic friction between fabrics decreased as the normal force per unit area increased. Wilson's model relating frictional force to normal force and the apparent area of contact closely correlated the data.

Molecular Tribometry: Recent Results and Future Prospects

The method of molecular tribometry is described. Ultrathin films of liquids are confined between parallel plates, usually of atomically smooth muscovite mica, such that the apparent area of contact equals the true area of contact. This paper consists of 5 sections. First, the phenomenon of solid lubrication by liquids is described. Second, the alternative viscous response of ultrathin liquid lubricants is described; the microviscosity is considerably enhanced over that of the isotropic liquid. Third, the critical shear strength is shown to have an extreme dependence on the normal pressure. Fourth, the materials requirements for molecular tribometry are discussed. Finally, a discussion is offered of the strengths and limitations of this new tool.

Analysis of the Local Deformations in Machine Joints

This paper presents a general method for calculating the pressure distribution and the deformations in machine joints. This method assumes that the components of the joint are connected through finite elements which are defined as a function of the surface finish, material and pressure at the apparent area of contact. The system so established is solved in an iterative manner using the finite-element method, obtaining, as a final result, the pressure distribution at the contacting surfaces of the components and the deformations of the surrounding body. To prove the validity and precision of the theoretical formulation, several examples of joints are considered where the correlation between the calculated and measured deflections is shown to be good.