ASTM B Type II and III zinc chromate plating Q&A’s. greater corrosion resistance is required, e.g., for SC3 & SC4 (13 & 25 microns zinc, respectively). Blue/Zinc. Blue/Zinc. Yellow/Zinc. Yellow/Zinc. ASTM B Type II SC 3 (FE/ZN 13). Type II SC 2 (FE/ZN 8). Type II SC 1 (FE/ZN 5). Type III SC 3(FE/ZN 13). ASTM A/AM Low and Intermediate Tensile Strength Carbon Steel Plates .. ASTM B Electrodeposited Coatings of Zinc on Iron and Steel.
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Iridescent and Colorless passivation is thin and has low electrical resistance. Regards, Ted Mooney, P. Zinc coating with colorful RoHS compliance passivation. Zinc ast is usually considered a functional coating, not a decorative one. The electrical resistance of this green layer passivation is very high because it is thick in relative to other passivations. Ken Vlach – Goleta, California.
The Zinc coating on the steel does not last shiny for long, and so a further thick layer coating is added, called passivation. Regarding the question asked in letter ; Type II zinc plating vs. The answer is Yes. Put the chromate on light.
Zinc Plating: ASTM B Type II vs. III
That seems a bit discretional to me. To calculate it is very difficult, as the plating is a few molecules thick. Hello Claudio and Doug, My compliments for an excellent round of atsm We are getting poor coverage on the as-cast surface of some steel castings using a yellow Zinc chromate.
ASTM B – Standard Specification for Electrodeposited Coatings of Zinc on Iron and Steel
Try using an acid zinc chloride bath and see if the casting covers. Please forgive any resultant repetition or failures of chronological order. I have the exact same questions. III zinc plating A discussion started in but continuing through Q.
Type II chromates are more commonly used where greater corrosion resistance is required, e. Olive Drab chromate is hrs.
Iron metals rust relative quickly, even in a non-corrosive environment.
So if I’m interpreting this correct, there is both a color difference and a salt spray difference. I b6333 to specify platings that do not contain Hexavalent Chromium for parts that will be used in the automotive industry. Any information would be well received. The part is currently being produced in China and my local platers are suggesting a dye to get a blue color. But if you are looking for something indisputably blue, as opposed to clear with a possible slightly bluish b6333, this probably requires dye.
Kaushik, The “Types” define supplementary finishes to be done after the plating.
Rest in peace, Ken. The type of passivation is determined according to the required characteristics, and is divided into groups:.
Ray Kremer Stellar Solutions, Inc. Could you explain this? Zinc coating with phosphate passivation. No, other colors may not be available if my presumption is right. The rust not only harms the aesthetically smooth look, but also its mechanic needs. Colorful chromate passivation gives corrosion resistance ability of 96 hours according to ASTM B until white spots-intended to parts used in a high corrosive environment —outdoor.
The end user must decide when a part fails, at “white rust” corrosion the chromate has failed or red rust both the chromate and the zinc are gone exposing the base metal. Trivalent chromates give paler and lighter finishes; some use metals, some use permanganates, some use dyes, in order to replicate the Hex finish. Can anyone give me some direction on how to get the customer to accept going to clear.
Does plating make that big a difference knowing that it’s going to be painted also? In 24 years I have only been asked this question once before and I presume it involves phosphating over zinc plating for those heavy phosphating grammage applications, where normal phosphating will not provide enough zinc phosphate that is required in the deposit. Different brands of chromate conversion chemistry, possibly different plating processes acid zinc vs. Corrosion resistance Colorful chromate passivation gives corrosion resistance ability of 96 hours according to ASTM B until white spots-intended to parts used in a high corrosive environment —outdoor.
Sorry, but if you need one particular look, you must go through the ugly process of maintaining sample boards with acceptable vs. Go to main content. All I need to know is what color the types are.
Until a very few years ago chromate conversion coatings were based on hexavalent chromium, and deposited a thick film that was relatively easy to dye. Hi, I recently received 2 batches of parts from two separate platers using this specification. The Zinc coating b6633 a smooth look as well as good anti-corrosive protection.
Zinc coating with colorful chromate passivation. Don Penzenik – Elkhart, Indiana.
A light yellow would be better than a clear. To me “bright blue” does not usually literally mean “bright blue” like the sky or a robin’s egg. Some of today’s proprietary trivalent chromium coatings are very thin and consequently will not generate a highly saturated color though. Electrical charasteristics As much as the last layer of the passivation is thin the electrical resistivity asrm low.