CHARACTERISTICS OF ADHESION BETWEEN SOIL AND SOLID-SURFACES

The capillary attraction and viscous resistance caused by a water film between two solid surfaces were evaluated theoretically. The surface morphology of soil at the soil-solid adhesion interface was examined b y scanning electron microscopy. The contact models of the soil adhesio n interface are given and mechanism of the normal adhesion is discusse d. The wettability and normal soil adhesion of polytetrafluoroethylene (PTFE) sheet, polyethersulforne (PES)-PTFE coating, enamel coating, i ron base alloy-epoxy composite coating and the conventional material w ere determined. The draft force of ploughs with mouldboards coated wit h PES-PTFE, enamel and iron base alloy-epoxy and the conventional moul dboard plough were measured. The soil surface at the soil-solid interf ace displays rough structure at various sizes. The adhesion force betw een soil and solid is mainly composed of Laplace pressure, meniscus te nsion and viscous resistance caused by water film and loops. Polymers can reduce both normal adhesion and sliding resistance, whereas, ename l coating or iron base alloy-epoxy composite coating can reduce the sl iding resistance to some extent.