Porosity refers to the number of pores per unit area. It is an important indicator to measure the quality of the coating. It can directly protect the protective performance of the coating. It is used for heat resistance. It is necessary for the coating in other environments to have an effective porosity.
Various thermal spraying methods are processing methods that make the sprayed particles stack on the surface of the body to form a protective layer, so there must be some holes in the layer. In the sprayed state, the porosity of the coating is usually 5%~15% About, when the thickness of the coating is below 0.2mm, there are often penetrating pores. As a wear-resistant coating, the holes in the coating can be used to protect the lubricant, accommodate the magic, and make the coating more wear-resistant, but it acts on the grinding stone or For industrial and mining corrosion, the condition is that the corrosive medium will penetrate the surface of the substrate through the holes, which will not only be harmful to the corrosion technology, but also reduce the bonding strength and easily cause peeling. The commonly used determination methods are as follows,
Coating Peeling Method
The experimental steps are as follows. First, the coating is separated from the body. Not only is there obvious unevenness in the appearance, but the coated jewelry is not placed in a room at 105-120 degrees, and dried in the air for about two hours to make the quality constant. Mass m1, put the dried 4 pieces into distilled water at room temperature in three steps, and infiltrate and exhaust them under vacuum. After the air bubbles are exhausted, take them out and weigh them. These 4 pieces are called 4 pieces of saturated water, and then use the diameter Thin metal wires below 0.5 mm, hang the saturated water event in the water and weigh, and the weighing value after deducting the weight of the metal wire is the water mass of the saturated water sample, m2. Finally, take the saturated water sample out of the water and quickly wipe it with a damp cloth Wipe it dry and weigh it as the weight m3 of the saturated water event, then the surface porosity can be calculated by the following formula.
Apparent porosity, (open porosity,) e=(m3-m1)/(m3-m2)*100%
