| It is well known that enamel materials are one kind of composite materials, which consist of enamel layers and metals. The adherence strength is one of the most important physical properties for enamel. The enamel quality mainly depends on the adherence strength of enamel materials.The enamel adherence agent, such as, CoO, NiO etc., plays a very important role in the adherence of enamel materials. According to the traditional enameling technology, enamel adherence agents, such as, NiO, etc. should be introduced into enamals by melting addition of NiO, the strong adherence strength cannot be achieved. The disadvantages of melting addition of NiO, are that the quantity of melting addition is high and the cost of enamel is more expensive, and the color of enamel is deep dark and the colorful enamel with one coat can not be developed, as well as the defects of fish scales can not be overcome by melting addition of CoO, NiO.In order to solve the disadvantage of melting addition of NiO, to increase the adhering performance of adherence agents and to overcome the enamel defects of fish scales, the super-fine crystal of Li2Ni8O10 (grain size: 0.1-0.5 um) is synthesized successfully by using the batch of Ni(NO3)2 and Li(CO3)2 ,and controlling the time and temperature of the crystal nucleus and crystal growth.The enamel materials with strong adherence strength are made successfully by mill addition of superfine crystal of Li2Ni8O10.In order to study the performance and mechanism of increasing the adherence strength of enamel materials, the chemical composition, crystal composition, microstructure and elements distribution at the interface between metallic iron and the enamel layer with the strong adherence strength, have been investigated with the help of scanning electron microscope, electron microprobe etc.It has been discovered by the study that the oxidizing-reducing reaction between metallic iron and nickel oxide has been accelerated by mill addition of superfine crystal of Li2Ni8O10, the reduced metallic nickel is concentrated on the interface between the enamel layer and metallic iron, and the alloy of Ni-Fe has been developed, which results in the crystal lattice deformation of iron and the adherence between metal and the non-stoichiometical transitional layer is achieved by the metallic bond and the adherence between the non-stoichiometical transitional layer and the enamel layer is produced by ionic and covalent bond. The non-stoichiometical transitional layer results in the strong adherence between the enamel layer and metallic iron. The enamel adherence theory of the non-stoichiometical transitional layer has been proposed. |
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