hans109h
Well-known member
I had some small parts that I decided would best be protected from rust by phosphatizing. I realize I could have heat treated with oil or cold blued the parts, but I wanted to learn more about the process commonly referred to as manganese Parkerizing. With a pretty good grasp of chemistry I dove into it and came up with a recipe that worked for me. This certainly isn't the only way to accomplish this, nor is it the best way--but since a simply step by step guide wasn't readily available I have decided to share my process here. Your results may very, and these can be very dangerous chemicals if you don't know what you're doing or how to work with them. Be safe.
Hanserizing Summary:
A. Degrease (Sodium Hydroxide)
B. Rinse
C. Etch (Hydrochloric Acid)
D. Rinse
E. Activate
F. Phosphate
G. Rinse
H. Oil impregnate
Process:
A. After taking my parts down to bare metal in the blast chamber I soaked them in a 10% solution of Sodium Hydroxide. To cover my parts I needed about a quarter liter so I dissolved 25 grams of NaOH (Sodium Hydroxide, Lye, crystal drain opener etc...) in 250 mL of water in a stainless steel container. I headed this solution to 80C on a single burner hot plate and soaked the parts for 5 minutes.
B. Following the degreasing I rinsed the parts in clean water for a few minutes.
C. To give the manganese a good surface to adhere to I etched the parts in a solution of 15% hydrochloric acid and hydrogen peroxide. I mixed 121 mL of 31% muriatic acid with 130 mL of water (adding acid into the water). This gave me 250 mL of 15% HCl. To this I added 5 mL of hydrogen peroxide. After a quick stir I added the parts and soaked for 3 minutes at room temperature.
D. Following the etching I rinsed the parts in clean water for a few minutes.
E. Think of activating in this process like priming if you were going to paint. You don't have to do it, but if you do you'll get finer crystalizing and a better end result with superior rust resistance. My recipe for activation was manganese phosphate and Sodium pyrophosphate. Manganese carbonate is easier to source than manganese phosphate so I first combined 4 grams of MnCO3 with 6.5 grams of 85% phosphoric acid. This gave me a thick bubbly paste (carbonate releases as CO2 and Magnesium attaches to the acid) which I placed in a half gallon of distilled water. To this mixture I added 8 grams of sodium pyrophosphate. I placed this on the hot plate and heated to 40C. I observed the acid and water reacting with the carbonate in the form of gas being released. I needed to wait for most of this conversion to take place so that I knew I had enough manganese phosphate available in the solution. When the bubbles mostly stopped I soaked the parts in this solution for 4 minutes. I transferred the mixture to a 1 gallon HDPE container for stroage.
F. Preparing the phosphating solution was similar to the activater. I measured out 67 grams of manganese carbonate and 84 grams of 85% phosphoric acid. I added the MnCO3 to 1/2 gallon of distilled water and then added the acid in a 316 (non-magnetic) stainless steel container. I placed this container on the hot plate and brought it to 95C. The goal was to get the reaction going as fast as possible without boiling off to much water. Again I waited for the CO2 to be released making the manganese phosphate available in the acid solution. After about an hour the mixture was cloudy but I could see a clear layer at the top which had settled down and wasn't releasing gas. I added enough distilled water, using the scale mark on the side of the container to return the mixture to the original volume. I used steel wire to attached to my parts and used the other end of the wire to hook onto the container so the parts were suspended in the solution. I submerged the parts for 15 minutes while maintaining the temperature at 95C. After the mixture had cooled I placed in in a 1 gallon HDPE container for storage. I discarded most of the remaining MnCO3 sludge that had formed at the bottom of the container. I assume this was a combination of impurities and undissolved MnCO3.
G. Following the phosphate bath I rinsed the parts in clean water for a few minutes.
H. After drying the parts I submerged them in ATF and left them to soak for 24 hours.
Process Summary:
A. Degrease (Sodium Hydroxide)
25 g NaOH + 250 mL H20, 5 minutes at 80C
B. Rinse
C. Etch (Hydrochloric Acid)
130 mL H20 + 121 ml HCl + 5 ml H2O2, 3 minutes at room temp.
D. Rinse
E. Activate
4 g MnCO3 + 6.5 G H3PO4 + 8 g NaP2O7, 4 minutes at 40C
F. Phosphate
67 g MnCO3 + 84 g H3PO4 + 1/2 gal distilled water, 15 minutes at 95C
G. Rinse
H. Oil impregnate
ATF (or any other suitable oil) for 24 hours
Additional information:
Sodium Hydroxide is usually the only ingredient in crystal drain openers soil at most hardware stores. This is a very inexpensive way to obtain it.
Manganese is not the same as magnesium. Make sure you know what you're using. Manganse Carbonate is easy to obtain is pretty soluble in an acid solution, much more so than manganese dioxide. If you have a local pottery supply company this would be a good source, but also available in various quantities on the interwebs. Manganese dioxide can be removed from batteries, this is a dirty process and you'll be left with a product that may work, but why?
I wasn't able to find a good source for a low quanity of sodium pyrophosphate, so I bought what will probably be a lifetime supply. It wasn't cheap, but didn't break the bank either.
The first time though I did the steps as I made the solutions, so for example, after the acid etching my parts sat exposed to air for a while until the next solution was ready. In hindsight I wouldn't have done this and would have had all of my solutions ready to go and at the proper temperature. In the photo below you'll see that some of the parts did develop some flash rust, and this probably should have been avoided.
There are additional ingredients that could be added to the phosphate bath such a nitrate (nitric acid), nickel....but the more of these that start going in the more dangerous the mixture, so I just kept it simple.
The solutions can be stored properly and reused over and over again, just keep the water at the right level of your original mixture. Depending on how often you use them you might have to eventually add additional manganese phosphate.
The oil impregnation step could be sped up significantly if with the use of a ultrasonic cleaner. I don't have one....
These are the parts after they were degreased, etched, and activated:
And here is the large nut after the process:
I did a couple of plain old nails that I'm going to do a salt water test on and compare to corrosion on a regular nail. If the test goes well I will report back.
Until then,
Hans
Hanserizing Summary:
A. Degrease (Sodium Hydroxide)
B. Rinse
C. Etch (Hydrochloric Acid)
D. Rinse
E. Activate
F. Phosphate
G. Rinse
H. Oil impregnate
Process:
A. After taking my parts down to bare metal in the blast chamber I soaked them in a 10% solution of Sodium Hydroxide. To cover my parts I needed about a quarter liter so I dissolved 25 grams of NaOH (Sodium Hydroxide, Lye, crystal drain opener etc...) in 250 mL of water in a stainless steel container. I headed this solution to 80C on a single burner hot plate and soaked the parts for 5 minutes.
B. Following the degreasing I rinsed the parts in clean water for a few minutes.
C. To give the manganese a good surface to adhere to I etched the parts in a solution of 15% hydrochloric acid and hydrogen peroxide. I mixed 121 mL of 31% muriatic acid with 130 mL of water (adding acid into the water). This gave me 250 mL of 15% HCl. To this I added 5 mL of hydrogen peroxide. After a quick stir I added the parts and soaked for 3 minutes at room temperature.
D. Following the etching I rinsed the parts in clean water for a few minutes.
E. Think of activating in this process like priming if you were going to paint. You don't have to do it, but if you do you'll get finer crystalizing and a better end result with superior rust resistance. My recipe for activation was manganese phosphate and Sodium pyrophosphate. Manganese carbonate is easier to source than manganese phosphate so I first combined 4 grams of MnCO3 with 6.5 grams of 85% phosphoric acid. This gave me a thick bubbly paste (carbonate releases as CO2 and Magnesium attaches to the acid) which I placed in a half gallon of distilled water. To this mixture I added 8 grams of sodium pyrophosphate. I placed this on the hot plate and heated to 40C. I observed the acid and water reacting with the carbonate in the form of gas being released. I needed to wait for most of this conversion to take place so that I knew I had enough manganese phosphate available in the solution. When the bubbles mostly stopped I soaked the parts in this solution for 4 minutes. I transferred the mixture to a 1 gallon HDPE container for stroage.
F. Preparing the phosphating solution was similar to the activater. I measured out 67 grams of manganese carbonate and 84 grams of 85% phosphoric acid. I added the MnCO3 to 1/2 gallon of distilled water and then added the acid in a 316 (non-magnetic) stainless steel container. I placed this container on the hot plate and brought it to 95C. The goal was to get the reaction going as fast as possible without boiling off to much water. Again I waited for the CO2 to be released making the manganese phosphate available in the acid solution. After about an hour the mixture was cloudy but I could see a clear layer at the top which had settled down and wasn't releasing gas. I added enough distilled water, using the scale mark on the side of the container to return the mixture to the original volume. I used steel wire to attached to my parts and used the other end of the wire to hook onto the container so the parts were suspended in the solution. I submerged the parts for 15 minutes while maintaining the temperature at 95C. After the mixture had cooled I placed in in a 1 gallon HDPE container for storage. I discarded most of the remaining MnCO3 sludge that had formed at the bottom of the container. I assume this was a combination of impurities and undissolved MnCO3.
G. Following the phosphate bath I rinsed the parts in clean water for a few minutes.
H. After drying the parts I submerged them in ATF and left them to soak for 24 hours.
Process Summary:
A. Degrease (Sodium Hydroxide)
25 g NaOH + 250 mL H20, 5 minutes at 80C
B. Rinse
C. Etch (Hydrochloric Acid)
130 mL H20 + 121 ml HCl + 5 ml H2O2, 3 minutes at room temp.
D. Rinse
E. Activate
4 g MnCO3 + 6.5 G H3PO4 + 8 g NaP2O7, 4 minutes at 40C
F. Phosphate
67 g MnCO3 + 84 g H3PO4 + 1/2 gal distilled water, 15 minutes at 95C
G. Rinse
H. Oil impregnate
ATF (or any other suitable oil) for 24 hours
Additional information:
Sodium Hydroxide is usually the only ingredient in crystal drain openers soil at most hardware stores. This is a very inexpensive way to obtain it.
Manganese is not the same as magnesium. Make sure you know what you're using. Manganse Carbonate is easy to obtain is pretty soluble in an acid solution, much more so than manganese dioxide. If you have a local pottery supply company this would be a good source, but also available in various quantities on the interwebs. Manganese dioxide can be removed from batteries, this is a dirty process and you'll be left with a product that may work, but why?
I wasn't able to find a good source for a low quanity of sodium pyrophosphate, so I bought what will probably be a lifetime supply. It wasn't cheap, but didn't break the bank either.
The first time though I did the steps as I made the solutions, so for example, after the acid etching my parts sat exposed to air for a while until the next solution was ready. In hindsight I wouldn't have done this and would have had all of my solutions ready to go and at the proper temperature. In the photo below you'll see that some of the parts did develop some flash rust, and this probably should have been avoided.
There are additional ingredients that could be added to the phosphate bath such a nitrate (nitric acid), nickel....but the more of these that start going in the more dangerous the mixture, so I just kept it simple.
The solutions can be stored properly and reused over and over again, just keep the water at the right level of your original mixture. Depending on how often you use them you might have to eventually add additional manganese phosphate.
The oil impregnation step could be sped up significantly if with the use of a ultrasonic cleaner. I don't have one....
These are the parts after they were degreased, etched, and activated:
And here is the large nut after the process:
I did a couple of plain old nails that I'm going to do a salt water test on and compare to corrosion on a regular nail. If the test goes well I will report back.
Until then,
Hans
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