Chemical Resistance

Chemical resistance refers to a material’s ability to maintain its structural and functional integrity when exposed to corrosive chemicals, solvents, or aggressive environments. This resistance is determined by a combination of material composition, structural properties, and surface engineering:

• Material Composition: The inherent makeup of a material — such as alloying elements in stainless steel or resin types in polymers — defines how it responds to specific acids, bases, or solvents.
• Surface Coatings: Protective layers like Armoloy Thin Dense Chrome (TDC), ceramic coatings, or epoxies form physical and chemical barriers that block corrosive agents from reaching the base metal.
• Cross-Linking in Polymers: Thermoset plastics and elastomers with high cross-link density resist molecular breakdown by creating stable, tightly bonded structures.
• Barrier Properties: Some materials act as diffusion barriers, slowing or preventing chemical penetration. Thin dense chrome, for example, offers low porosity and high chemical inertness, ideal for corrosive industrial or food-grade environments.

Chemical resistance is a key property in applications such as chemical processing, medical devices, semiconductors, and marine equipment, where long-term exposure to reactive substances must not compromise performance.

Chemical resistance is evaluated using standardized test methods that measure how a material responds to chemical exposure — including changes in weight, strength, surface appearance, and dimensional stability. These tests simulate real-world conditions to assess long-term durability.

Common Testing Methods:

• Immersion Testing: Materials are submerged in specific chemicals for set durations; changes in mass, hardness, tensile strength, or visual degradation are recorded.
• Vapor or Splash Exposure: Samples are exposed to chemical vapors or splashes in controlled chambers to observe surface and structural effects.
• Dynamic or Flow-Through Testing: Used for components exposed to circulating fluids, measuring chemical resistance under realistic flow and pressure conditions.
• Standardized Protocols: Tests like ASTM D543 (plastics), ASTM G31 (metal immersion), and ISO 1817 (elastomers) define test duration, chemical type, and evaluation metrics.

These methods help engineers determine material compatibility, validate protective coatings, and ensure safe performance in industries like chemical processing, medical devices, and semiconductors.

Good chemical resistance means that a material can endure prolonged exposure to a variety of chemicals without significant deterioration or loss of properties. Characteristics of good chemical resistance include:

• Durability: The material remains physically and chemically stable over time when exposed to chemicals.
• Minimal Swelling or Degradation: The material does not absorb chemicals or swell excessively, which can lead to loss of mechanical integrity.
• Retention of Mechanical Properties: The material retains its strength, flexibility, and other mechanical properties after chemical exposure.
• Low Permeability: The material does not allow chemicals to pass through easily, maintaining a barrier to protect underlying surfaces or structures.

Materials like certain grades of stainless steel, fluoropolymers (e.g., PTFE), and specialized coatings are known for their excellent chemical resistance, making them suitable for use in harsh chemical environments.