The thickness variation of high-temperature resistant coatings may have various impacts, as follows:The impact on protective performance
Changes in high temperature resistance performance:
Thinning situation: If the coating thickness becomes thinner, its resistance to high temperature environments will decrease. For example, a coating that could originally withstand a high temperature of 1000 ℃, due to its reduced thickness, makes it easier for heat to be conducted to the substrate at high temperatures, accelerating the substrate's oxidation, deformation, and other damage processes. This cannot effectively protect the substrate from high-temperature corrosion and shorten the service life of the substrate and the entire component.
Thickness increase: When the coating thickness increases, although it can enhance the high temperature resistance to a certain extent, if it exceeds the reasonable range, it may cause cracking, peeling and other phenomena of the coating itself due to internal stress accumulation, which will affect its overall high temperature protection effect and cannot effectively protect the substrate from normal use in high temperature environments.
Reduced corrosion resistance:
Thinning effect: When the coating thickness decreases, external corrosive chemicals (such as acid, alkali, salt spray, oxidizing gases, etc.) are more likely to penetrate the coating and come into contact with the substrate, increasing the risk of substrate corrosion. For example, in chemical production, in high-temperature environments with acidic gases present, coatings that could effectively isolate acidic gases become thinner and difficult to prevent gas from corroding the substrate, resulting in substrate corrosion and affecting its performance and structural integrity.
Thickening effect: When the coating is too thick and has defects such as pores, corrosive substances may penetrate into the interior of the coating and accumulate within it, accelerating the corrosion damage of the coating itself. Moreover, once the thick coating is locally corroded, it is more likely to spread, deteriorating the corrosion resistance of the entire coating and failing to ensure the safety of the substrate.
The impact on bonding strength
Thinning thickness: Thinning the coating will relatively reduce the bonding area between the coating and the substrate. Some bonding strengths that were originally maintained by mechanical interlocking and chemical bonding between the coating and the substrate will be affected. For example, when there is thermal stress or mechanical external force, the coating is more likely to peel off from the substrate because its thickness is not sufficient to provide sufficient bonding force to resist these external forces, resulting in a decrease in the stability of the connection between the coating and the substrate.
Thickness increase: Overly thick coatings are prone to accumulate significant internal stresses, which may exceed the bonding strength between the coating and the substrate under temperature changes, external forces, and other conditions. This can cause the coating to detach from the substrate or crack, damaging the bonding state between the two and seriously affecting the bonding strength. In addition, when local defects appear in thick coatings, they are more likely to propagate, further weakening the overall bonding strength.
The impact on component size and assembly
Size change: Changes in coating thickness can directly cause changes in the overall size of the coated component. For example, on some precision mechanical components, if the thickness of the high-temperature resistant coating exceeds the design range and becomes thicker, it will increase the outer diameter, thickness, and other dimensions of the component, which may affect its fitting accuracy with other components, leading to assembly difficulties and inability to install it properly into the corresponding equipment, affecting the assembly and operation of the entire equipment.
Post assembly impact: Even if the components can be assembled smoothly, if the coating thickness changes during subsequent use, it may damage the original assembly gap and fit relationship, causing increased friction and wear between components, and even leading to malfunctions such as jamming, affecting the normal operation and service life of the equipment.
The impact on the stability of the coating itself
The stability issue of thinning: After the coating thickness is reduced, its structural integrity is damaged and becomes more fragile. Under high temperature, chemical, mechanical and other effects, it is more prone to damage, peeling and other situations, which cannot maintain a stable existence state, further accelerate the failure process, and cannot continue to play the necessary protective functions.
Stability issues with thickening: Overly thick coatings have poor stability due to high internal stress, susceptibility to defects, and difficulty in releasing stress. They are more prone to cracking, delamination, and other phenomena during use, making it difficult for the coating to maintain good performance in the long term, affecting its stability and reliability throughout the entire service life.
In short, changes in the thickness of high-temperature resistant coatings, whether they become thinner or thicker, will have adverse effects on various aspects such as protective performance, bonding strength, component size, and coating stability. Therefore, it is necessary to strictly control the coating thickness and monitor and maintain it during use.

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