Influence of Surface Conditions on Wear and Friction of Hardmetals

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Bargaining theory and the analysis of Belgian multy-party-government formation during the interwar period

Koalitionsbildung und insbesondere die Verteilung der Ministersessel unter den Koalitionspartnern ist das Ergebnis eines komplexen kollektiven Entscheidungsprozesses. Der vorliegende Beitrag untersucht dieses 'bargaining' von einem spieltheoretischen Ansatz her. Als Testfall dient die belgische Mehrparteienregierung während der Zwischenkriegszeit. Die tatsächliche Verteilung der Ressorts wird mit der aus dem Modell abgeleiteten Prognose verglichen. (pmb)'The distribution of minister portfolios in government coalitions is the result of a complex process of bargaining. In that way power relations among political parties are reflected in the distribution of cabinet posts. In this paper the predictions of game theoretical concepts (bargaining set, -core) and the Gamson hypothesis are compared with the actual portfolio distribution. In most Belgian interwar governments the relatively small liberal party was able to obtain a share of ministeries substantially larger than their share of parliamentary seats in coalition. Game theoretical models proved superior in capturing this effect. They also accentuate the disruptive effect of the 1936 elections. The success of extreme parties changed the simple bargaining structure of the 1919-1936 period into a complicated one. Moreover, the 1936 game is as far removed as possible from a Pareto optimal solution, which explains the labourious formation of short-lived governments.' (author's abstract

Effect of surface finishing on tribological properties of ZrO2-based composites

Laboratory-made ZrO2-based composites with 40 vol. % WC, TiCN or TiN were tested in dry sliding contact with WC-6wt%Co cemented carbide using an ASTM G133 pin-on-flat configuration. Surface characterization included profilometric measurement, scanning electron microscopy, energy disperse X-ray analysis and X-ray diffraction. ZrO2-based composites with wire-EDM surface finish displayed higher friction coefficient and wear level compared to their ground equivalents. This finding was correlated to flexural strength measurements, revealing strong discrepancy between both surface finishes. ZrO2-WC composites exhibited superior tribological characteristics compared to the ZrO2-TiCN and ZrO2-TiN grades

Dry sliding friction and wear response of WC-Co hardmetal pairs in linearly reciprocating and rotating contact

This paper presents an experimental evaluation of friction and wear properties of WC-Co cemented carbides. A comparison is made between unlubricated rotating and linearly reciprocating pin-onplate sliding pairs. The plate specimens were WC-10wt%Co grades surface finished by polishing or sequential wire-EDM steps, whereas WC-6wt%Co pins were used as counter body. The tests were carried out at room temperature using a sliding speed of 0.30m/s and mean Hertzain contact pressures of 1.76 and 2.08 GPa, i.e., normal contact loads of 15N and 25N, respectively. The worn surfaces on plate samples were quantified in terms of 2–D wear profiles obtained by means of surface topography scanning equipment. Wear mechanisms such as polishing and abrasion were identified using optical microscopy. Inferior tribological characteristics for wire-EDM surface finish compared to polishing were found. Higher friction coefficient and wear levels were measured in unidirectional rotating sliding experiments compared to linearly reciprocating test conditions