Weather-resistant materials

Definition (material type and key properties)

Weather-resistant materials are metals, polymers, elastomers, composites, and coatings engineered to retain mechanical integrity, appearance, and functional performance during prolonged outdoor exposure. They resist degradation mechanisms such as ultraviolet (UV) radiation–induced embrittlement and discoloration, hydrolysis and moisture ingress, corrosion from salts and pollutants, ozone and oxidative attack, thermal and freeze–thaw cycling, environmental stress cracking, and surface chalking or gloss loss. Performance may be intrinsic (for example, fluoropolymers or corrosion-resistant alloys) or achieved via stabilization packages (UV absorbers, HALS, antioxidants), protective coatings, surface treatments, and multi-layer architectures. Typical evaluation metrics include:

  • UV weathering (ASTM G154/G155; ISO 4892), with retention of tensile/impact strength and appearance (color ΔE, ASTM D2244; gloss, ASTM D523)
  • Corrosion resistance (ASTM B117; ISO 9227; cyclic corrosion such as SAE J2334; VDA 233-102)
  • Water uptake and hydrolysis resistance (ISO 62 for plastics), ozone resistance (ASTM D1149 for elastomers)
  • Barrier performance where relevant (water vapor transmission rate, WVTR; oxygen transmission rate, OTR)
  • Thermal/humidity/freeze–thaw cycling and stone-chipping durability (e.g., ISO 20567), plus natural exposure testing (e.g., multi-year Florida/Arizona/Kalahari)

Benefits and typical use cases

  • Extended service life and reliability: Maintains strength, toughness, sealing, and electrical properties in sun, rain, snow, and temperature extremes; lowers lifecycle cost.
  • Aesthetics and surface integrity: Preserves color, gloss, transparency, and texture; mitigates chalking, yellowing, crazing, and cracking.
  • Corrosion protection and safety: Reduces metal loss, fastener seizure, and galvanic attack; improves enclosure integrity and ingress protection (IP) for electronics.
  • Reduced maintenance: Slows repainting/recoating cycles and component replacement in harsh climates.

Typical use cases include:

  • Transportation: Exterior automotive/EV trim, fascias, mirror housings, roof rails; underbody shields and brackets; coated chassis parts; lamp and sensor housings; weatherstrips and glazing seals.
  • Buildings and infrastructure: Façade panels and cladding, roofing and gutters, architectural coatings, window profiles, outdoor signage and furniture.
  • Energy and marine: Solar module frames and backsheets, wind-turbine coatings and composites, marine hardware and railings, dock fixtures.
  • Electronics and equipment: Outdoor enclosures for telecom, charging stations, lighting, and industrial controls; connectors, cable jackets, and grommets.

Relevance (processing and surface engineering)

  • Polymers and composites: Injection molding, extrusion (profiles, sheets, films), thermoforming, compression molding (SMC/BMC), RTM, pultrusion, filament winding. Weatherability enhanced through compounding with UV absorbers, HALS, antioxidants, TiO2 or carbon black pigments, barrier layers via co-extrusion, and UV-resistant gelcoats or clearcoats.
  • Elastomers and sealants: EPDM extrusion and vulcanization, liquid injection molding for silicones, TPV/TPE overmolding; stabilization with anti-ozonants, wax bloom, and UV packages.
  • Metals: Hot-dip galvanizing (HDG), zinc and zinc–nickel electroplating, conversion coatings, anodizing (aluminum), e-coat, powder coating, and multilayer paint stacks; advanced barriers via PVD/CVD or thermal spray. Surface preparation (cleaning, phosphating, silanes) is critical for adhesion and longevity.
  • Coatings: 2K polyurethane and acrylic topcoats, fluoropolymer coatings (PVDF, FEVE) for premium weathering, UV-curable systems for rapid processing; primers and sol–gel sealers to improve adhesion and corrosion undercutting resistance.

Validation and performance metrics

  • Accelerated weathering: ASTM G154/G155 or ISO 4892 with property retention targets (tensile/impact, ΔE, gloss).
  • Corrosion: Neutral salt spray (ASTM B117; ISO 9227) and cyclic protocols (SAE J2334; VDA 233-102) to simulate road salts and wet/dry cycles.
  • Moisture/thermal cycling: Humidity exposure, freeze–thaw, and thermal shock to assess cracking, delamination, and seal performance.
  • Mechanical/erosion: Stone chipping (ISO 20567) and abrasion tests for coating durability.
  • Functional: Water ingress (IP ratings), dielectric strength/creepage for electrical parts, and dimensional stability after exposure.

Examples and related terms

  • Polymers and blends: ASA and AES (weatherable styrenics), UV-stabilized ABS, PMMA for optical clarity, UV-stabilized PC and PC/ASA, stabilized PBT and PA for electrical housings, UV-stabilized HDPE (often carbon-black filled).
  • Elastomers: EPDM for weatherstrips and gaskets; silicone for high-UV/high-temperature seals; TPV/TPE with UV/ozone packages for overmolded seals and trims.
  • Metals and treatments: Aluminum with anodizing or durable paint stacks; stainless steels (e.g., 304/316) in high-corrosion zones; weathering steels for architectural use; HDG or Zn–Ni plated steels with e-coat and powder/paint topcoats.
  • Composites and films: GFRP/CFRP with UV-resistant gelcoats; SMC body panels; fluoropolymer films and coatings (PVDF, FEVE) for long-term color/gloss retention.
  • Synonyms/related terms: Weatherable materials, outdoor-durable materials, exterior-grade materials, UV-stable materials, weatherproof materials, corrosion-resistant materials, marine-grade materials.

Selection and design considerations

  • Choose stabilization suited to climate and exposure (UV index, altitude, humidity, salt, pollution); darker colors with carbon black and white with rutile TiO2 typically weather best.
  • Use compatible multilayer systems (primer/topcoat synergy; co-extruded caps) and ensure proper surface preparation for adhesion.
  • Manage geometry and joints to avoid standing water, mud traps, and crevices; isolate dissimilar metals to prevent galvanic corrosion; allow for thermal expansion in plastics/composites.
  • Validate with both accelerated and natural exposure; correlate to real-world conditions and define end-of-life property thresholds.

Further information: suitability for EV applications

  • Exterior lightweight components (composite body panels, aerodynamic trims, charge-port doors) benefit from UV-stable polymers and coatings that maintain color, gloss, and impact strength.
  • Corrosion-resistant metals/coatings extend life of battery enclosures, underbody shields, and high-voltage cable brackets exposed to road salts and debris.
  • Ozone/UV-resistant elastomers preserve sealing for battery packs, cooling circuits, and IP-rated connectors, limiting water ingress and maintaining dielectric clearances.
  • Weather-stable polymers and coatings protect sensors, cameras, and lidar windows, maintaining optical clarity; outdoor charging hardware and enclosures retain mechanical and electrical performance across wide climatic and duty cycles.