The Influence on Boundary Friction of the Permeability of Sintered Bronze

Abstract

Components made of sintered bronze are often used in tribological systems. Examples of applications are self lubricated bearings, wet clutches and brakes and synchromesh components for manual gearboxes. The bronze material in these applications is often porous and permeable. However, the required level of permeability i.e., the ability for a fluid to flow inside the material varies widely for different applications. This implies the need to investigate if the permeability can influence the properties of a tribological system. Various studies have been performed in order to investigate the permeability of different materials but a possible relationship between permeability and boundary lubrication performance has not yet been thoroughly investigated. In this article this relationship has been investigated in a pin-on-disk apparatus for test specimens with a permeability that is well-defined. Materials with three different permeabilities were investigated together with non-permeable test specimens. The results indicate that permeability has a small influence on the friction coefficient when the tribological system is operating with good lubrication of the contact. The function of the tribological system when working under starved conditions is also investigated and a very clear relationship between permeability and the ability to cope up with starved running conditions is shown. This is explained in terms of the varying ability of the materials' to store lubricant in pores. Non-porous test specimens were also tested as a comparison with the permeable test specimens in the investigation with starved running conditions . The results show that a material with high permeability works much better under starved running conditions than that with low permeability.

Lubricant ageing effects on the friction characteristics of wet clutches

“…A characteristic of sintered materials is their porosity. The pores in the material can act as reservoirs for the lubricant and capillary forces keep the fluid in place [14]. An image of the sintered bronze surface taken with a scanning electron microscope (SEM) can be seen in Fig.…”

Tin-bronze cladding on thin steel sheet by cold metal transfer arc deposition

“…Tin bronze has excellent corrosion resistance, fatigue resistance, wear resistance as well as high strength [1][2][3], and it is usually cladded on the thin steel sheet in order to form the tin bronze/steel bimetallic sheet, which can be used to make various kinds of bearings and bushes [4][5][6]. Tin bronze cladding layer prepared by traditional powder sintering process has problems such as high porosity and coarse grain [7,8]. Therefore, there is a need to study a new method for fabricating tin bronze layer on thin steel sheet.…”

Simulation of the engagement of carbon fabric wet clutch: Analytical and experimental comparison

“…Fei et al [4] studied the influence of the composition of friction materials on the dynamic friction torque during engagement. Marklund et al [5] investigated the effect of the permeability on the temperature during engagement. It was found that the permeability can affect engagement time, temperature of the clutch and boundary lubrication friction coefficient.…”