Novel Ni-P-Tribaloy Composite Protective Coating

Area of Science:

• Materials Science
• Corrosion Engineering
• Tribology

Background:

• Oil and gas pipelines require robust protective coatings against damage and degradation.
• Electroless Nickel-Phosphorus (Ni-P) coatings offer good wear and corrosion resistance but lack toughness.
• Composite coatings can improve toughness by incorporating second-phase particles.

Purpose of the Study:

• To develop and evaluate a Ni-P-Tribaloy composite coating for enhanced pipeline protection.
• To investigate the effect of Tribaloy particles on the mechanical and tribological properties of Ni-P coatings.
• To assess the toughening mechanisms and fracture toughness of the composite coating.

Main Methods:

• Co-deposition of Tribaloy (CoMoCrSi) particles into a Ni-P matrix on low-carbon steel.
• Micro-hardness testing to assess mechanical strength.
• Hertzian indentation and scratch testing to evaluate fracture toughness and wear resistance.

Main Results:

• A Ni-P-Tribaloy composite coating with 15.7 vol.% Tribaloy was successfully fabricated.
• Micro-hardness increased by 12% compared to monolithic Ni-P coating.
• Fracture toughness was quadrupled, with observed toughening mechanisms including micro-cracking, crack bridging, arrest, and deflection.
• The composite coating exhibited superior sliding wear resistance and more ductile behavior.

Conclusions:

• The addition of Tribaloy particles significantly enhances the toughness and wear resistance of Ni-P coatings.
• Ni-P-Tribaloy composite coatings are a promising solution for improving the durability of oil and gas pipelines.
• The observed toughening mechanisms contribute to the superior performance of the composite.