Anyone Electrolytically etching?

[Car 54]

I’ve found that there are some variables involved such as the type of NP metal and the age of the acid. I always found that the alloys containing Be etched better than those without...but who wants to use that stuff today??!



Sent from my iPad using Tapatalk

Thanks. It's been awhile for me, it sounds like you have a better handle on it

Agree as far as using NP. I gave up on that ~ 10 years ago. But I did like the nice light oxide layer with Rex 3.

 

[ztech]

In the 80's electrolytic etching was the only way we etched them. What may be the problem in this case is the etch gel may be for the wrong alloy. Most Maryland bridges are made from a Nickel/Chrome alloy. The etch attacks the nickel and that gives you the retentive surface. Problem is, many alloy manufacturers have gone away from nickel due to patient sensitivity to it. Even the electrolytic units used reagents to remove nickel. Check your alloy, if it doesn't have nickel, contact one of the companies that sell the etching gel and get the one that will work with your alloy.

 

[ps2thtec]

In the 80's electrolytic etching was the only way we etched them. What may be the problem in this case is the etch gel may be for the wrong alloy. Most Maryland bridges are made from a Nickel/Chrome alloy. The etch attacks the nickel and that gives you the retentive surface. Problem is, many alloy manufacturers have gone away from nickel due to patient sensitivity to it. Even the electrolytic units used reagents to remove nickel. Check your alloy, if it doesn't have nickel, contact one of the companies that sell the etching gel and get the one that will work with your alloy.

Wow that gave me a flashback to my first lab job. We had one of those consoles with dials,meters and lights.
Coat the porc with wax and attach wires and with roachclips, suspend the MB in acid. Even today seems like voodoo. Within a few months the bridge would be back for another etching.
A temporary solution to a permanent problem !

 

[2thm8kr]

and with roachclips

 

[Sda36]

In the 80's electrolytic etching was the only way we etched them. What may be the problem in this case is the etch gel may be for the wrong alloy. Most Maryland bridges are made from a Nickel/Chrome alloy. The etch attacks the nickel and that gives you the retentive surface. Problem is, many alloy manufacturers have gone away from nickel due to patient sensitivity to it. Even the electrolytic units used reagents to remove nickel. Check your alloy, if it doesn't have nickel, contact one of the companies that sell the etching gel and get the one that will work with your alloy.

My understanding is that when etching metal ie acid that it's the Beryllium thats etched out leaving a nice etched surface for bonding. Beryllium has come under a lot of scrutiny in the last several years making it no longer present in a number of alloys. I know Tilite contained it still at last look but could be wrong. Used to love that alloy for Pfm's, still occasionally see some old ones due to root fracture etc. and sent along fir shade match. Metal work is still pristine after 15- 20 years.

Sent from my LG-H873 using Tapatalk

 

[ztech]

Beryllium is etched with Potassium hydroxide, the common acid used to etch maryland bridges is an acid compound that contains nitric ,sulphuric, hydrochloric which etches nickel and chromium. The reason not to etch the beryllium is because it is such a small component of the alloy. It is less than 2% and is added to enhance the castability. NiCr alloys contain around 70% nickel and 30% chromium which gives the alloy a good surface etch with the compound etches.

 

[Sda36]

Beryllium is etched with Potassium hydroxide, the common acid used to etch maryland bridges is an acid compound that contains nitric ,sulphuric, hydrochloric which etches nickel and chromium. The reason not to etch the beryllium is because it is such a small component of the alloy. It is less than 2% and is added to enhance the castability. NiCr alloys contain around 70% nickel and 30% chromium which gives the alloy a good surface etch with the compound etches.

Good to know, thanks for clarifying ztech!

Sent from my LG-H873 using Tapatalk

 

[ztech]

Good to know, thanks for clarifying ztech!

Sent from my LG-H873 using Tapatalk

Not a problem. All those years studying every year for promotion in the Air Force has it's perks. We have a lot of sometimes useless information in our heads.

 

[Sda36]

Not a problem. All those years studying every year for promotion in the Air Force has it's perks. We have a lot of sometimes useless information in our heads.

I used to use a similar acid mixture for chemically polishing pure Ti. One thing I noted was reaction was really rather different depending on sample size ie small unit vs large one. Large actually started giving off a visual brown gaseous vapor and it was STOP NOW once. That ended my use of that treatment protocal, dangerous mixture for sure. I think my mix was 40% Hydroflouric, 40 Sulfuric and 20% Nitric but thats going back to 1987...

Sent from my LG-H873 using Tapatalk