Development of a micro-droplet technique for wettability studies: Application to the Al-Si/SiC system
- Univ. of Oxford (United Kingdom). Dept. of Materials
In order to study the wetting behavior of liquid metals it is common practice to use the sessile drop technique for measuring contact angles. However with reactive metals, such as aluminium, true wetting behavior is obscured by the presence of oxide films surrounding the molten metal drop. To overcome this problem the authors have developed a technique using micro-droplets. in these experiments evaporation or sputtering is used to deposit a metal film on the ceramic surface. The thin film is heated up under vacuum and micro-droplets form on the ceramic surface after melting. Contact angles can be measured, after solidification, by tilting the specimens in a SEM. This technique can also give some information about surface reactions. When a droplet forms and retracts after the melting of the deposited film, it leaves behind reaction products if any reaction has taken place. In this case, unlike the macro sessile drop experiments where advancing contact angles occur, retracting angles are measured. The microwetting technique described can be used to study the wetting behavior of reactive metal systems on ceramics at low temperatures when, in the normal sessile drop experiment, stable oxide films obscure the true wetting behavior of the metal. In this method retracting contact angles are measured unlike the normal sessile drop technique where advancing contact angles usually occur. The technique can be extended to study any metal alloy system via adjustment of target element area fractions in the sputtering deposition process. It is a comparatively easy process to prepare.
- OSTI ID:
- 105959
- Journal Information:
- Scripta Metallurgica et Materialia, Vol. 33, Issue 5; Other Information: PBD: 1 Sep 1995
- Country of Publication:
- United States
- Language:
- English
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