HEX FREE Chem Conversion Coating for Alum Alloys
Featured Product from CHEMEON Surface Technology, LLC
CHEMEON TCP-NP (hex free) is chemical conversion coating on aluminum alloys with high corrosion protection, excellent adhesion qualities for subsequent paint and powder coat, low cost, quick and easy processing, and all while meeting the stringent requirements of military specifications. It is QPL pending for the immersion, spray, brush and touch-up pen application by the United States Navy-Defense Standardization Program under governing Spec MIL-DTL-81706B. Unlike conventional conversion coating treatments, NP (No-Prep) won’t require any deox or surface activation step. This will shorten the processing time, increase output rate and lead to significant savings.
Salt Spray Corrosion: Five (3x10 in2) 2024-T3 and five (3x10 in2) 7075-T6 panels were processed with CHEMEON TCP-NP at room temperature (65-75 °F) for 5 min and cured at room temperature for 24 hrs. Cured samples were subjected to a 5% neutral salt fog test in accordance with ASTM B-117 for 336 hours. After exposure, test panels were cleaned in running water at ~60 °F, forced air dry, and visually examined for conformance to MIL-DTL-81706. There was no sign of corrosion or pit formation on both alloy types after 336 hours of salt spray exposure.
Coating weight: Coating weight analysis was done on CHEMEON TCP-NP processed three 2024- T3 (3x10 in2) and three 7075-T6 (3x10 in2) aluminum alloys in accordance with MIL-DTL-81706. Coating weight for all methods of application is more than 20 mg/ft2 depending on the method of application.
Paint Adhesion: Epoxy primer conforming to MIL-PRF-23377 (High solids) with dry film thickness of ~ 0.7 mil was applied on CHEMEON TCP-NP processed two (3x10 in2) 2024-T3 and two (3x10 in2) 7075-T6 panels. Wet tape adhesion tests were done in accordance with FED-STD-141, Method 6301.3. No visible flaking of separation of the epoxy from the panel beyond the cuts. No visible removal from the chemical film and no damage to the chemical film.
Electrical Contact Resistance: CHEMEON TCP-NP processed 6061-T6 panels were tested for the LER (Low Electrical Resistance)
As-Processed: 1090 ± 5.6 microhms/in2
After 168 hrs salt spray: 1136 ± 6.2 microhms/in2.