24th International Colloquium Tribology - January 2024 57 Introducing a New High-Performance Water-Based Rust Preventive Additive for Formulations Demanding Superior Metal Parts Protection in Severe Corrosion Conditions Clifford Pratt, Ph.D. 1* 1 King Industries, Inc. Norwalk Connecticut USA * Corresponding author: cpratt@kingindustries.com 1. Introduction Protection of metal parts against corrosion, including everything from small to large components, remains a critical element in the financial investment of parts manufacturing. Most high-performance rust preventive formulations consist of petroleum oil and petroleum derived solvents in combination with rust preventive additives. Solvents typically make up 30% to 95% of the rust preventive formulation. Evaporation of these petroleum derived solvents poses a serious pollution problem in many areas of the world. Given the shift driven by environmental regulation from the market dominant oil-solvent based rust preventives to water-based formulations, a gap has emerged in products that provide adequate protection. For water based formulations, King Industries already has a solid line of rust preventive additves that give either emulsion or clear solution type formulations. Formulations based on these products offer excellent multi-metal protection under high humidity conditions; however, none provide adequate steel protection in high salt environments. A new rust preventive additive based on King Industries’ unique calcium dinonylnaphthalene sulfonate technology, CP-46, has been developed for use in water-based systems to fill the gap, providing superior performance in high humidity and specifically high salt containing atmospheres. Through a series of ASTM, DIN, and in-house tests, this new product, CP-46, has demonstrated exceptional corrosion protection performance in addition to emulsion stability under stressed conditions. This new additive combines the performance, stability, and versatility expected in traditional RP systems without the concerns of handling volatile solvents, which is better for the environment and eliminates worker exposure to hazardous VOC’s. 2. Sample Preparation CP-46 has been designed to first be added to oil then emulsified with ordinary tap water. For this study, the Standard CP- 46 emulsion refers to the following formulation: 10% CP-46 20% ISO VG 32 Group I Oil 70% Norwalk CT Tap Water This emulsion is extremely stable and has been observed for over 90 days without showing signs of separation. Alternate formulations with different oil types, including some esters, along with different ratios of CP-46 to oil, were also evaluated. The resulting emulsions based on these alternate formulations are also extremely stable, and the results are examined in depth in the presentation. 3. Experimental To evaluate the rust protection performance of CP-46 formulations, a combination of standardized and in-house test methods was used. 3.1 Salt Fog (ASTM B117) CP-46 was designed for high salt environments, therefore, a significant portion of the testing in this study involved Salt Fog (ASTM B117) evaluations. Because ASTM B117 is a practice, only the chamber conditions are specified, and several other test parameters including test pieces, specimen preparation, and failure criteria are left to the user to define. The test specimens were all prepared in a consistent manner defined by King Industries, and the rust preventive formulation was applied by dipping. For this study, failure was defined as rust that extends more than 1.5 cm from the top edge of the panel and/ or 0.5 cm from either side edge. The edges of the panels were not taped. Uncoated panels fail very quickly in this test. Figure 1 shows significant rust formation on an uncoated panel after 1 hour of exposure. Figure 1: Salt Fog (ASTM B117) Testing on Uncoated 1010 Steel Q-Panel. 30 minutes (left) and 1 hour (right) of exposure Salt Fog testing was reviewed on many different metal alloys showing the exceptional protection obtained by using CP-46. Figures 2 and 3 show examples of the Salt Fog testing results of the Standard CP-46 Formulation on steel and aluminum panels, respectively. 58 24th International Colloquium Tribology - January 2024 Introducing a New High-Performance Water-Based Rust Preventive Additive for Formulations Demanding Superior Metal Parts Protection ... Figure 2: Standard CP-46 Formulation. Salt Fog (ASTM B117) Testing on 1010 Steel Q-Panels. Average hours to failure: 140 (polished, front), 72 (matte, rear) Figure 3: Standard CP-46 Formulation. Salt Fog (ASTM B117) Testing on 2024/ T3 Aluminum panels. Average hours to failure: 85 - 90 (polished) 3.2 Humidity (ASTM D1748) High humidity testing on multi-metal alloys was also evaluated per ASTM D1748. Unlike ASTM B117, the humidity cabinet method clearly defines cabinet conditions, panel preparation steps, and failure criteria for the panels evaluated, and those parameters were followed for this study. Similar to the Salt Fog testing, panels were coated with the rust preventive formulation by dipping. CP-46 provides excellent rust protection under high humidity conditions to a variety of metal alloys with and without added oil. Figure 4 highlights the protection provided by the previously defined Standard CP-46 Formulation on steel panels. Figure 4: Standard CP-46 Formulation. Humidity Cabinet (ASTM D1748) Testing on 1010 Steel Panels. Average hours to failure: 2892 3.3 Acid Atmosphere (In-house) King Industries has also developed an in-house test for Acid Atmosphere to help evaluate which rust preventive additives would work well for protecting metal stored near pickling lines or anywhere hydrochloric acid fumes are present. In the test, coated panels are hung from the lid of a test chamber that has 200 mL distilled water in the bottom as well as a beaker containing 50 mL of a 6% HCl solution. The chamber assembly is placed in an oven at 40°C, and each side of the test panel is monitored for corrosion. Failure has been defined as more than 20% rust per side. CP-46 was evaluated in this in-house acid atmosphere chamber in three formulations to examine the effects of varying the amount of oil on the level of protection provided. Average Hours to Failure 10% CP-46 5% ISO VG 32 Group | Oil 85% Tap Water 306 10% CP-46 10% ISO VG 32 Group | Oil 80% Tap Water 666 10% CP-46 20% ISO VG 32 Group | Oil 70% Tap Water 818 4. Summary CP-46, King Industries’ new water emulsifiable rust preventive concentrate, has many attributes that make it well suited for formulating water-based rust preventives: • Exceptional multi-metal rust protection performance under severe conditions including salt fog, high humidity, and acid atmosphere. • Compatibility with a variety of oils that can then be easily blended with water to make very stable emulsions. • Low foam emulsions leading to versatility of application methods (brush, spray or dip). • Excellent Humidity Cabinet (ASTM D1748) corrosion protection with or without added oil. • Rust protection booster of semi-synthetic and oil soluble metal working fluids. • Easily removable thin films using common alkaline detergents. • VOC solvent free.