What Does Microcrack Mean?
A mcrocrack is a type of material damage consisting of cracks small enough to require magnification to observe. A microcrack is an indication of material failure that can ultimately lead to complete failure. It may occur on a coating during the application or drying process, or during load strain of a coating or material.
With microcracking, a material’s strength, stiffness and stability decrease, possibly leading to undesirable properties such as a failure to protect the underlying materials from environmental contact and corrosion. Microcracks may form before the strain on a material reaches its breakpoint. As such, strain on materials should be limited before the resin fibers start to break.
Corrosionpedia Explains Microcrack
Normally we can determine when a material will break under strain from measures such as tensile strength. However, close to the ultimate level of strain may be strain levels at which fibers of the resin slowly start to debond. This debonding of the polymeric material will eventually spread to form microcracks along the material.
The microcracks do not immediately have a detrimental effect on the material. However, environmental contaminants, such as moisture, will be absorbed into the material in greater quantities than for an uncracked material. Water absorption, for example, increases the weight of the material and reduces stiffness. If the water can penetrate a coating's surface or concrete protection over a metallic frame, then corrosion rates may become enhanced.
The occurrence of microcracking depends on the adhesion and toughness properties of the material or coating. Choosing tougher or more adhesive formulations of coatings will provide higher microcracking strain levels, preventing the formation of microcracking and subsequent damage. Understanding the probability of microcracking is important when choosing a coating system. Some brittle resin systems may only be capable of sustaining 10% of its resistance to strain before microcracks form.