Jakob Weiland Høj

Thermal Characterisation of Brake Pads

The chemical-physical decomposition processes that occur in a brake pad heated to 1000°C have been studied. This temperature can be reached when a brake pad is applied. Thermogravimetry and differential thermal analysis were used in combination with evolved gas analysis, and image analysis using a scanning electron microscope.A brake pad is essentially a mixture of iron, carbon and binder. Combined techniques have been used,because of chemical reaction overlap, to determine how and at what temperature the binder decomposes, the coal and graphite combust and the iron oxidises.This work enables the development of brake pads that are stable at high temperature.

On the chemical nature of boundary lubrication of stainless steel by chlorine- and sulfur-containing EP-additives

Abstract The nature of the extreme pressure (EP) effect of the dialkylpolysulfides and chlorinated paraffins during the ironing of stainless steel AISI 304 has been studied. A strip reduction test was used in combination with differential thermal analysis (DTA), profilometry, X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy analysis (AES). Strip reduction tests, in which chlorinated paraffin and dialkyl sulfide were compared as EP-additives, have shown significantly stronger EP-effect of the chlorine containing lubricant, than for the sulfur containing lubricant. DTA analysis of the Me-powder (where Me=iron, chromium or nickel)–dialkylpolysulfide (or chlorinated paraffin) mixtures have shown that dialkylpolysulfide was chemically active with iron and nickel (the highest activity was with nickel). Chromium was practically nonactive with dialkylpolysulfide. Chlorinated paraffin was equally active with iron, chromium and nickel. The better lubrication performance demonstrated by chlorinated paraffin compared to dialkylpolysulfides was attributed to the chemical activity of the chlorinated paraffin with all the main components of stainless steel. The depth profiles of the stainless steel strips were examined before and after strip reduction by use of AES sputter profiling. Results imply that the chlorine containing lubricant enforces the formation of a thick oxide layer.

A new closing method for wall flow diesel particulate filters

A new method has been developed to close the ends of a wall flow filter used for removing particulate matter from diesel engine exhaust. In this method, the ends of the honeycomb structure are capped by deforming and closing the ends of the channel walls between the extrusion and firing stages of production. The method increases the amount of filtration area per filter volume for a given cell geometry compared to the traditional plugging method, since the entire length of the honeycomb channels is used for filtration purposes. In addition, use of the capping method has a beneficial effect on the pressure loss characteristics of a filter with a given filtration area. These benefits are illustrated through experimental results.