Liquid Ceramics
Want higher adhesion strength? Higher resistance to chemicals? Superior resistance to abrasion? This coating alternative provides unprecedented increases in surface protection.
The array of coatings and coating methods employed to improve the resistance of pumps, impellers, mixers and other metal surfaces subjected to corrosion, chemical attack, and abrasion has grown dramatically over the years.
These coating options have slowly evolved into increasingly more effective solutions that are divided into general groups, including: industrial paints, rubber coatings, fiber reinforced polyester, build-up by welding, flame spraying, special metal alloys, special plastic materials, and filled epoxy coatings.
All of these provide protection - albeit in varying degrees - against specific corrosive or chemical environments. Some have also made significant progress in the reduction of abrasive damage.
Most recently, advances in solvent-free, ceramic-filled polymeric coatings (known as liquid ceramics) and specialized coating methods (i.e., airless spraying) have resulted in an exponential increase in the levels of surface protection and abrasion resistance that are practically achievable.
Durability Begins with Adhesion Strength
Most dramatically, the adhesion strength of liquid ceramics is several times stronger than the adhesion strength of conventional coating and coating methods.
Liquid ceramics regularly achieve adhesion rates in the range of 15 Newtons per-square-mm. A jump in coating adhesion levels on this scale is unprecedented in coating history.
An adhesion strength of 15 Newtons per-square-mm compares with primers containing zinc that have an average adhesion strength of just 2.5 Newtons per-square-mm, and industrial paint coatings that have adhesion strengths ranging from one-quarter Newton to four Newtons per-square-mm. Typically, two-component coatings with high levels of solids have an adhesion strength in the range of six Newtons per-square-mm - still less than half that of liquid ceramics.
Chart A. Adhesion comparison between four major types of coatings. Adhesion strength is basic to the effectiveness of any coating.
The importance of adhesion strength in increasing the effective life of a coating can hardly be overestimated, because two of the key elements in the destruction of protective coatings act against adhesion strength.
One of these is the pressure exerted by iron corrosion. This is no small force, either. Iron (FE) expands its volume by 2.4X when oxidizing and creates a pressure just over 4 Newtons per-square mm on the backside of any coating when it is present. This pressure is enough to break the bonds of most paints and two-component coatings.
The second of these key elements-of-destruction is osmotic pressure, which can exert a force of almost three Newtons per-square-mm to the bonding layer of a coating.
This in no way diminishes the importance of the inherent application characteristics of a coating, which can have a significant effect on its adhesion. For example, solvent-based coatings are slow to evaporate and develop microscopic capillaries that allow intrusion of moisture and other environmental agents - often leading to the formation of iron corrosion.
When liquid ceramic coatings are applied under proprietary conditions, no capillaries structures or air cavities are developed to interfere with the exceptionally high adhesion strength of the coating.
Salt Spray Tests Reveal the Difference
ASTM salt spray tests (5 percent at 28-deg C) have demonstrated that primers containing zinc begin to fail at 500 hours. Likewise, typical industrial paint coatings failed at just 100 hours, and two-component coatings with a high percentage of solids fail at 350 hours.
Chart B. Corrosion resistance comparison between four major types of coatings. Salt spray tests prove the importance of adhesion.
In these same corrosion resistance tests, the liquid ceramics coating endured 10,000 hours of salt spray without signs of corrosion, at which point the test was ended.
Chemical Resistance Counts, Too
Coatings vary widely in their resistance to specific chemicals and classes of chemicals.
For example, epoxy-type two-component coatings are subject to damage by alkalis, whereas polyester-based coatings can be weakened when exposed to certain acids and salts, even in low concentrations. Both epoxies and polyesters are adversely affected by organic solvents.
Liquid ceramics are resistant to moderate levels of acids (ten to twenty percent solutions for most, and double that for acids such as hydrochloric acid). Liquid ceramics are also resistance to all bleaches and alkalis at moderate-to-high concentrations, and have a very high resistance to other compounds such as salt water, sewage, kerosene, naphtha, toluene, and other organic chemicals.It's All About What They Are Made Of
Surface hardness is critical to protection from the affects of abrasion. Because of the high ceramic content of liquid ceramic (as the name implies) its hardness numbers are double that of conventional coatings.
Next, there is the issue of coating thickness and how it is developed. The thickness of an epoxy-tar coating, for example, is 15-mils - developed in four layers, beginning with a zinc primer (with an adhesion capacity of four Newtons or less) that is usually built up by the addition of three successive layers. Liquid ceramics, by comparison, are created as a single homogenous layer of at least 16-mils.
Conclusion
Liquid ceramics - with their extremely high adhesion strength, high resistance to chemicals, and superior resistance to abrasion - provide a highly effective solution for most coating challenges.
This relatively new, but thoroughly proven, coating option is an exponential advance in the capabilities of coatings, and welcome news in the fight to increase the useful life of pumps, impellers, and mixers from the daily environmental ravages they face.
Liquid ceramics conquer the enemies of coated metal with incredible adhesion levels - almost 4X stronger than oxidation forces (aka rust) and 5.5X stronger than osmotic forces. Add to this the hardness numbers that are double that of ordinary coatings, and combine it with chemical resistance levels that are the envy-of-the-industry, and what you have is, unquestionably, a winner.
