Finite Element Analysis of Ceramic Coating Systems Under Spherical Indentation With Metallic Interlayer: Part I — Uncracked Coatings

Spherical indentation problems of ceramic coatings/metallic inter-layer/ductile substrate were investigated numerically by axisymmetric finite element analysis (FEA) for two typical ceramic coatings with relatively high and low elastic modulus deposited on aluminum alloy and carbon steel. Various indenter radius-coating thickness ratios and interlayer thickness-coating thickness ratios were used in the modeling. Radial stress distribution and plastic damage zones evolution were discussed in connection with model parameters. The results showed that the suitable metallic interlayer could improve resistance of ceramic coating systems through reducing the peak tensile radial stress on the surface and interface of ceramic coatings and plastic damage zone size in the substrate under spherical indentation.

Roles of Surfactant Molecules in Post-CMP Cleaning

One major concern in post-CMP cleaning is particles contamination on the substrate surface after the CMP process. These particles can be abrasive particles from the slurry, debris from pad material, and particles of film being polished. The cleaning method used in this study is direct contact of the substrate surface and brush sweeping. To enhance the cleaning process, an anionic surfactant is added in the cleaning solution. In order to understand effects of surfactant molecules on post-CMP cleaning, for the first time, we use a tribological approach over a range of surfactant concentration and temperature. In this regard, we observe how the surfactant behavior before and after it reaches the critical micelles concentration (cmc). Experimental results show that increase in surfactant concentration can promote bilayer interaction of micelles on the hydrophilic particles. Based on our study, we propose an interactive explanation of surface molecules with the wafer surface and nanoparticles through friction. This understanding will serve as a guide on how much surfactant should be added in order to achieve effective particle removal.

A Micro-IRRAS Study of Lubricant Degradation Under Thin Film Conditions

This paper studies lubricant degradation in a rubbing contact under thin film conditions. Friction tests have been carried out in an MTM test device using a steel ball/steel disc configuration. The tests were run with a small amount of lubricant present. At the end of the test the disc was retained for analysis. Micro-reflection FTIR spectroscopy was used to analyse the lubricant chemistry within and close to the rubbed track. The technique offers a more direct method for studying lubricant degradation products during rubbing. The results are compared to those from more conventional experimental methods.

Widening Classical Wear Laws to the Concept of Third Body

During the second part of the twentieth century, many efforts have been done to model wear. Particularly, Archard proposes in 1953 [1] one of the first wear law, which is often written on the following form: dW/dt=K.P.V(1) with dW/dt the mass of detached particles from the rubbing materials per unit time, P the applied pressure, V the sliding speed and K the “wear rate”.

Study on Lubrication Properties of Carboxymethyl Cellulose as a Novel Additive in Water-Based Stock

This paper reports cellulose derivative—carboxymethyl cellulose (CMC) as a novel additive in a water-based stock (water content above 95 wt.%). Cellulose is one of the richest renewable resources on earth and has many peculiar qualities. Several cellulose derivatives such as CMC can easily dissolve in water and form stable thin film on the surface of metal. Several apparatus involving four-ball machine were used to investigate lubrication properties of the based stock containing CMC. The worn surfaces were observed with a scanning electron microscope. As the results, the anti-wear ability of the base stock is effectively increased by addition of a small amount (0.7 wt.%) of CMC. The additive with peculiar molecular structure contributes to abate the adhesion and scuffing of frictional pair effectively, hence improves the antiwear ability of the base stock. Thus CMC provides a potential application in the field of water-based stock lubrication.

Ceramic Rolls for Wires, Tubes and Sheets

The main reason for using ceramic materials for metal working tools is the significantly higher wear resistance with respect to commonly used steel tools and therefore the possibility to improve the lifetime as well as the product quality. Ceramic rolls were developed and tested in different applications. In this paper the work on the development of the ceramic rolls and the evaluation of several roll types in field tests are summarized.

Soft EHL Lubrication of Complex Multiphase Fluids

The lubrication properties of a series of multiphase water-based fluids of complex rheology and microstructure, including o/w emulsions, have been studied in a rolling-sliding steel ball-on-elastomer flat contact. The results show that friction curves of Newtonian fluids made over a wide range of entrainment speeds and viscosity can be used to identify the prevailing mechanisms of lubrication for more complex fluids and, for emulsions, to show the predominant film-forming phase.

Tribological Behaviour of GFR Polymer Composites

On a Pin-on-Disc test rig with composite disc and steel pin tribological experiments were done on pultruded glass fiber reinforced polymer matrix composites plates. The wear and frictional behavior strongly depends on the structure. Also the normal load plays an important role in the frictional behavior, which is of greater importance than the speed. The formation of a thin polymer film onto the wear track results in a lowering of the coefficient of friction with 20%.

Synthesis of the Multifunctional Additive N-acyl Glutamic Acid and Application in Water-Based Lubricating Fluids

A series of N-acyl glutamic acid were prepared by reaction of glutamic acid with chlorides (1–3) or anhydrides (4–8) in good yield, within the solution of pH 8–10, keeping the reaction at 10∼15°C for 2–3 hours. The tribological behaviors of the resulting N-acyl glutamic acid salts with triethanolamine as additives in water were examined on a four-ball machine. The rust-inhibiting properties were evaluated. The elemental composition of the boundary lubricating film was analyzed by means of auger electron spectroscopy (AES). It was found that the N-acyl glutamic acid with long acyl chain functioned to considerably increase anti-wear and friction-reducing abilities of water. The rust-inhibiting properties got better with increase of the length of acyl-chain of N-acyl glutamic acid triethanolamine slats. And the additives had relative good antimicrobial properties in water.

Relating Surface Roughness to Subsurface Stress

Understanding and anticipating the effects of surface roughness on subsurface stress in the design phase can help ensure that performance and life requirements are satisfied. The specific approach taken in this work to address the goal of improved surface design is to relate surface characteristics of real, machined surfaces to subsurface stress fields for dry contact. This was done by digitizing machined surfaces, simulating point contact numerically, calculating the corresponding subsurface stress field, and then relating stress results back to the surface. The relationship between surface characteristics and subsurface stress is evaluated using several different approaches including analyses of trends identified through stress field visualization and extraction of statistical data. One such approach revealed a sharp transition between cases in which surface characteristics dominated the stress field and those in which bulk, or global contact effects dominated the stress. This transition point was found to be a function of the contact operating conditions, material properties, and most interestingly, the roughness of the surface.