The presence of metals and their alloys in even hundredths and even thousandths of a percent gases and non-metallic impurities significantly reduces their strength and ductility. To purify metal from unwanted impurities gases, oxides, nitrides, and other non-metallic inclusions a set of technological operations that can be combined under the term of refining is developed. The process of refining is an absolutely vital part of improving the quality of metals and alloys.
Purification of the liquid metal from non-metallic inclusions is to separate the melt surface tiny gas bubbles and particles of oxides, nitrides, sulfides, and other compounds which normally remain in the melt and fall into an ingot. In recent years, combined methods for refining are gaining momentum – physical and adsorptive methods are meant. Absorptive refining method implies introducing inert or reactive gases into the melt to have impurities decomposed into gaseous products. Due to the low pressure gas within these bubbles is diffused in the dissolved metal hydrogen, nitrogen, and other gases and bubbles are adsorbed on the surface of the solid particles of nonmetallic inclusions. After achieving considerable size bubbles refining agents resurfacing molten metal. For sufficiently complete removal of non-metallic inclusions from the melt must pass through metal refining a large number of substances, which is not always appropriate and feasible.
Physical refining methods, e.g. vacuuming, require additional equipment and time to process metal.
The power of ultrasound
The use of ultrasound for the impact of a number of processes in the preparation and processing of metals and alloys is sufficiently well known and theoretically justified. Currently, ultrasonic methods of influencing interfacial surface metals in the liquid and solid state have acquired significant commercial importance due to the industry innovators like Hilsonic, providing a range of cost-effective ultrasonic cleaner equipment.
A significant number of published studies on the effects of ultrasound on metal melts demonstrates that ultrasound treatment is one of the most promising ways to regulate properties of the solid. These works consider mainly the possibility of using ultrasound during solidification of the melt. However, implementation of this method in the method of manufacturing products directly from the melt prevents a number of circumstances. Additionally, scoring to complete crystallization requires input of ultrasonic vibrations directly into the molded part, but this is not always feasible.
The most reasonable and promising way to improve the properties and structure of the products is the ultrasonic treatment of the liquid metal. Ultrasonic treatment of steels and other alloys studied to a lesser extent. One reason for the lack of studies of the effect of the ultrasonic field at the molten steel is the lack of reliable and efficient devices operating at high temperatures, as well as methods for administering ultrasound directly in the liquid metal.