Hyrdrofluoric nitric acid pickling - Page 3
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    Quote Originally Posted by Robert R View Post
    The cleaning/etching companies may also be concerned about maintaining part geometry during a acid etch. They may not be able to control etch rates inside part cavities or along sharp edges. There is too much risk involved in processing a expensive part and having it scrapped due to uneven etching. The company would need to do a trial etch on a number of test pieces and send them back to the customer for inspection prior to making a bid. Even then, there would not be a 100% success rate. A few parts in each batch might be out of specification. The etch rate would vary from part to part depending on the amount of oxidation or contamination from cutting fluids.

    The request for a acid etch is also vague. The quote needs to include one of the military or ASTM specifications so that there is no misunderstanding as to what is required.


    Some trivia:
    When processing zirconium or hafnium the hydrofluoric acid is used to remove the metal.. The nitric acid is used to capture the hydrogen that is produced to prevent it from being absorbed by the part.

    When processing tungsten or molybdenum the nitric acid oxidizes the metal and the hydrofluoric acid is used to remove the oxide.

    The do it yourself approach would require a glove box with a exhaust fan capable of maintaining a negative pressure in the box. The box would have a temperature controlled recirculating etch sink, fast flowing DI cold water rinse sink, a DI hot water rinse sink, and a hot air blow off.
    Robert R.

    The pickle spec calls for 1minute dip in cold or 30seconds dip in warm. Presumably this is extracted from another spec, somewhere.

    I expect 1minute is not going remove anything but oils. Which is the sole pickling intent.

    Thank you for the review. We found someone to do the pickling, still waiting for a quote....from anyone. How many days have I spent now?

    Sent from my SM-G975U using Tapatalk

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    Quote Originally Posted by claya View Post
    I expect 1minute is not going remove anything but oils. Which is the sole pickling intent.
    Oils are removed by ultrasonic solvent cleaning or a alkaline chemistry cleaning. . Acid pickling is used as a final cleaning step to remove oxides, contaminates, or metal fragments that the initial process cannot remove.

    Your customer has requirements other than removing oil.

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    Quote Originally Posted by claya View Post

    I expect 1minute is not going remove anything but oils. Which is the sole pickling intent.
    Now that's funny

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    Quote Originally Posted by Robert R View Post
    Oils are removed by ultrasonic solvent cleaning or a alkaline chemistry cleaning. . Acid pickling is used as a final cleaning step to remove oxides, contaminates, or metal fragments that the initial process cannot remove.

    Your customer has requirements other than removing oil.
    "Ditto"

    That is a trifle concerning.


    My thought is OK so everything goes to plan , then what metals and alloys are now in solution ? So the HF aspect had been neutralized what of the various heavy metals in solution ?

    Also wondering how much ultra precision Wire EDM and precision hole poppers and micro machining have replaced Metal etched components ? *

    @Robert R you mention metals and alloys used in the nuclear industry and more high energy high frequency electronics - in California if older processes are being phased out then surely that creates an opportunity for alternative techniques in California as many such related companies may not be so inclined to up-sticks and move to a different state. ~Thinking about your points you made about 'etch" geometry and artifacts. + process repeatability.


    __________________________________________________ ______________

    * Not sure how the disposal of Wire EDM filters go for "Dodgy/ extreme" metals ?

    ____________

    @Claya is the print and component belong to something that's 30 + years old by any chance ?

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    Quote Originally Posted by cameraman View Post
    "Ditto"

    That is a trifle concerning.


    My thought is OK so everything goes to plan , then what metals and alloys are now in solution ? So the HF aspect had been neutralized what of the various heavy metals in solution ?

    Also wondering how much ultra precision Wire EDM and precision hole poppers and micro machining have replaced Metal etched components ? *

    @Robert R you mention metals and alloys used in the nuclear industry and more high energy high frequency electronics - in California if older processes are being phased out then surely that creates an opportunity for alternative techniques in California as many such related companies may not be so inclined to up-sticks and move to a different state. ~Thinking about your points you made about 'etch" geometry and artifacts. + process repeatability.


    __________________________________________________ ______________

    * Not sure how the disposal of Wire EDM filters go for "Dodgy/ extreme" metals ?

    ____________

    @Claya is the print and component belong to something that's 30 + years old by any chance ?
    Nope, New design. We are considering alternate pickling processes. But they have a very specific concern for hydrocarbon based oils. Trace metallics, surface oxides did not come up in the conversation.

    Sent from my SM-G975U using Tapatalk

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    What type of hydrocarbon is best removed by acid?

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    Quote Originally Posted by claya View Post
    Nope, New design. We are considering alternate pickling processes. But they have a very specific concern for hydrocarbon based oils. Trace metallics, surface oxides did not come up in the conversation.

    Sent from my SM-G975U using Tapatalk
    Normally HF could be used (in very dilute solutions) for 'Degreasing" ,

    More typically acetone or something like 1,1,1, Trichloroethane (Chlorinated hydrocarbons being phased out) that have their own problems + laws can be acceptable degreasers. Acetone (laboratory grade) is good - (not the cheap stuff from the paint industry that has MEK, naphtha, toluene and other nasties in there) . Various alkaline solutions also as mentioned by Robert. R. + ultra sonic cleaning as Robert R. mentions. + other chelating agents.

    Bit of a dead end if the metal / alloy / application is unknown.

    The folks you are making this for know what they are doing ? / Speccing ?

    Is this a cosmetic effect or something that is functional for something optical / nano ?


    Or something related to high energy physics ?

    Have I missed something - you haven't stated the alloy or material or general field of application ?

    ______________________________________


    " Acid mix: 20%HF/20%Nitric/60%Diwater "

    ^^^ That's your stated "Mix" 20% HF seems to be the inflection point between quite nasty and super nasty i.e. 48% HF solution.

    So 20% HF (aq) is what the bloke/ gizer is doing in the bath tub etching video from post #39.

    The HF can be diluted and neutralized... Just wondering about the other metals now in solution ?

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    Quote Originally Posted by cameraman View Post
    Normally HF could be used (in very dilute solutions) for 'Degreasing" ,

    More typically acetone or something like 1,1,1, Trichloroethane (Chlorinated hydrocarbons being phased out) that have their own problems + laws can be acceptable degreasers. Acetone (laboratory grade) is good - (not the cheap stuff from the paint industry that has MEK, naphtha, toluene and other nasties in there) . Various alkaline solutions also as mentioned by Robert. R. + ultra sonic cleaning as Robert R. mentions. + other chelating agents.

    Bit of a dead end if the metal / alloy / application is unknown.

    The folks you are making this for know what they are doing ? / Speccing ?

    Is this a cosmetic effect or something that is functional for something optical / nano ?


    Or something related to high energy physics ?

    Have I missed something - you haven't stated the alloy or material or general field of application ?

    ______________________________________


    " Acid mix: 20%HF/20%Nitric/60%Diwater "

    ^^^ That's your stated "Mix" 20% HF seems to be the inflection point between quite nasty and super nasty i.e. 48% HF solution.

    So 20% HF (aq) is what the bloke/ gizer is doing in the bath tub etching video from post #39.

    The HF can be diluted and neutralized... Just wondering about the other metals now in solution ?
    This has veered way off from the original post. We are under non-disclosure. Yes, the customer knows what they are doing. A lot of good info on HF.

    BTW, 1,1,1 was banned in 1996.

    Sent from my SM-G975U using Tapatalk

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    Quote Originally Posted by claya View Post
    This has veered way off from the original post. We are under non-disclosure. Yes, the customer knows what they are doing. A lot of good info on HF.

    BTW, 1,1,1 was banned in 1996.

    Sent from my SM-G975U using Tapatalk
    Not really you keep asking about how to dispose of the used solutions/chemicals...

    If you have super toxic metals in solution then you have a disposal problem. "Small batches" - I.e. what you point to as being too expensive / difficult. + Rick Finsta alluded to your eventual metals problem*.


    Unless your substrate / material is glass or quartz etc.

    __________________________________________________ ____________

    * I believe in the nuclear industry they have experimented with fusing various radioactive metals into borosilicates/ various stable (soda)-glasses to stop availability of toxic + radioactive metals to the environment.

    It may be that what you are doing is not any more toxic than throwing away or burying a AA battery and a tube of toothpaste in your back yard ?

    If the only reason for using HF was degreasing seems laboratory grade acetone would be a safer alternative + the concentration for HF is rather (unnecessarily) high for that.

    I've made a deliberate point of not making this / exploding this thread into a political discussion... So I can't comment or extend the discussion to the Montreal Protocol and large scale industrial use of various classes of chemicals (specific chlorinated hydrocarbons / various isomers) vs. laboratory use for the same.

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    Quote Originally Posted by cameraman View Post
    in California if older processes are being phased out then surely that creates an opportunity for alternative techniques in California as many such related companies may not be so inclined to up-sticks and move to a different state.
    When you send a batch of cutting tools to the Balzers coating facility in California they first do a ultrasonic alkaline cleaning step to remove oil. The tools are then loaded into the chamber on fixtures. The first vacuum processing step is a ion etch to remove oxides, contaminates, and metal fragments. The multi layer coating is then deposited. The latest machines can do the process in four to six hours.

    The semiconductor industry made the transition from wet etching to glow discharge etching in the late1970's. The wet process had too many limitations and it was expensive to dispose of the waste. The glow discharge processes produces a solid waste and contaminated vacuum pump oil. The contaminated oil problem was solved by making the transition to dry vacuum pumps in the 1990's.

    There is still a need for acid etching in the semiconductor and tool coating businesses to clean vacuum chambers, deposition shields, fixtures, and ceramic electrical insulators. I suspect that the companies that do this work do not want to deal with small quantities of machined parts with unknown contamination.

    For example, a acid tank that is reserved for removing titanium nitride would not be used for cleaning mystery parts even if the acid mix was exactly what the mystery parts customer wanted The shop might be forced to dispose of the etch tank contents after the unknown contamination causes a failure of parts of a long term customer. It is not worth the trouble and there is a risk of damaging their reputation when something goes wrong.

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    Quote Originally Posted by Robert R View Post
    <snip> <All good / very cool>


    For example, a acid tank that is reserved for removing titanium nitride would not be used for cleaning mystery parts even if the acid mix was exactly what the mystery parts customer wanted The shop might be forced to dispose of the etch tank contents after the unknown contamination causes a failure of parts of a long term customer. It is not worth the trouble and there is a risk of damaging their reputation when something goes wrong.
    ^^^ Exactly.

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    Quote Originally Posted by claya View Post
    Nope, New design. We are considering alternate pickling processes. But they have a very specific concern for hydrocarbon based oils. Trace metallics, surface oxides did not come up in the conversation.

    Sent from my SM-G975U using Tapatalk
    I would try a local analytical lab, perhaps Evans in Sunnyvale. They have to mix up chemistry to do various things so might be able to do this for you and the part size will fit into a plastic beaker.

    The usage seems weird, HNO3/HF is a great metal etch for certain metals like Titanium. If they're only concerned about organic residue, there should be other options and the concentrations seem high.

    HF freaks me out and we used to use it by the gallon. The good thing about the other nasty things is you usually have some warning you're in trouble and should get in the shower or run.

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    Quote Originally Posted by -cg View Post
    I would try a local analytical lab, perhaps Evans in Sunnyvale..
    The lab work would settle the question of what cleaning process is required.

    Try this:

    Wash the part in Alconox and hot DI water in the ultrasonic tank. (SEE NOTE BELOW))
    Rinse with hot DI water.
    Apply a a second DI water rinse with a sprayer.
    Use a hot air dryer to blow off the water.

    Place the part in a plastic bag and send it off to Evans.

    Have the lab check for carbon contamination on the part using their energy dispersive X-ray analyzer (EDX) installed on the scanning electron microscope (SEM)

    Have the lab do a nitric acid- hydrofluoric acid dip for 60 seconds on the part followed by a DI water rinse.

    Have the lab repeat the SEM-EDX analysis and compare the before and after etch results.

    They will charge 4 hours labor for the work but it will save your customer a unnecessary cleaning expense in the long run.

    The failure analysis labs keep the acids on hand for examining grain boundaries on metal specimens.
    They are experts at contamination surveys.

    NOTE: The part can easily become contaminated with oils from careless handling, contaminated compressed air, shop coolant vapor, and plastic bags that have mold release additives.

    It is unlikely that you will be able to successfully clean the part in a machine shop environment. This work should be done by the customer. The other problem is that the machine shop has no control over careless handling of the part once it arrives at the customers shop. All it takes is someone forgetting to wear gloves or placing the part on a table top to recontaminate the part with oil.

    In some industries a cleaned part needs to be double bagged. The outer bag that becomes contaminated during handling is removed prior to entering the clean room.

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    Quote Originally Posted by claya View Post
    This has veered way off from the original post. We are under non-disclosure. Yes, the customer knows what they are doing. A lot of good info on HF.

    BTW, 1,1,1 was banned in 1996.

    Sent from my SM-G975U using Tapatalk
    Clay,
    Don't be foolish.
    You have been informed in a public forum that what you want to do has a fair to middling chance of causing injury or a hideous death. To you...

    My conclusion about this is that in order to handle this material properly your first step should be to get a job as an employee with a company that does thins stuff.
    Then spend several years getting yourself schooled by professionals.
    See what things look like at first hand when they go both well and wrong.

    On Monday, call whoever carries your or whole life insurance policy and ask them straight up if your policy has an "I'm to Pretty" clause.
    This is the clause that allows them to tell your wife that they don't pay claims for willfully ignorant behavior.

    If he or she is honest with you you will learn that your wife will have the distinct "pleasure" of learning from the attorney probating your estate that your can't collect on your policy for negligent behavior.

    With all of this knowledge in hand, ask yourself if handling this stuff is worth it.
    Doing so is like having an F450 for your every day driver in Willow Glenn.
    You will get a lot of looks but your penis won't be any bigger.

    I may seem a little abrupt in my language but just finished a couple of hours with the Old Testament in church.

    Practical Machinist is one of the industries great resources.
    It is not, however, a substitute for experience or training..

    Don't be stupid.

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    Quote Originally Posted by cameraman View Post
    Normally HF could be used (in very dilute solutions) for 'Degreasing" ,


    Have I missed something - you haven't stated the alloy or material or general field of application ?
    No, he hasnít...and if you know anything about that alloy, you should realize heís not going to.

    I referred him to my best friend...he deals with this stuff on the daily. We talk about work often.....Iíll ask what heís working on and most often he responds that he canít tell. Only that itís really cool stuff!


    Sent from my iPhone using Tapatalk

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    Quote Originally Posted by snowman View Post
    No, he hasn’t...and if you know anything about that alloy, you should realize he’s not going to.

    I referred him to my best friend...he deals with this stuff on the daily. We talk about work often.....I’ll ask what he’s working on and most often he responds that he can’t tell. Only that it’s really cool stuff!


    Sent from my iPhone using Tapatalk
    Aye,

    I think @Claya will probably figure out what he needs to figure out.

    But I wonder if the group pushing "Mystery alloy" onto Claya means that he starts to acquire an ever growing collection of jars of "Mystery metal" in solution with no plan for their disposal.

    Claya is already handling concentrated acids. If he's just winging it with what he already has then he probably has a 1 in 25 to one in one hundred chance of having an incident. If he's more prepared and careful maybe a one in two hundred to one in two thousand chance of having an incident. If he's following ALL the procedures for HF then maybe a one in five thousand to ten thousand chance of getting into some sort of trouble that can probably be ameliorated. Most of the very deep procedures are to make sure that any such accidents are a one in a million occurrence or less or mitigate substantially worst case scenarios and least skillful users (once being availed of the risks , dangers and various procedures thereof + investment in appropriate level of safety equipment.).

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    Bullshit.

    Most of the procedures are in place to satisfy underwriting, or safety concerns in large corporate environment which are completely different from small businesses. You can buy some pretty nasty shit at the hardware store...and letís not even talk about the superfund site that is any of our grandparents gardening shed.

    Both large corporations and tiny companies have a central theme of ensuring documentation and appropriate labeling. These are the most important.

    The difference is, in sole proprietor land, you have a lot more control over who accessibility...ie, who needs to be trained and who could be the innocent bystander.

    The challenges faced by the sole proprietorship is largely in ethical disposal should you get hit by a truck. Ie, the poor wife that has to clean up your mess.

    Beyond that itís just a matter of being safe.


    Sent from my iPhone using Tapatalk

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    Quote Originally Posted by snowman View Post
    Bullshit.

    Most of the procedures are in place to satisfy underwriting, or safety concerns in large corporate environment which are completely different from small businesses. You can buy some pretty nasty shit at the hardware store...and let’s not even talk about the superfund site that is any of our grandparents gardening shed.

    Both large corporations and tiny companies have a central theme of ensuring documentation and appropriate labeling. These are the most important.

    The difference is, in sole proprietor land, you have a lot more control over who accessibility...ie, who needs to be trained and who could be the innocent bystander.

    The challenges faced by the sole proprietorship is largely in ethical disposal should you get hit by a truck. Ie, the poor wife that has to clean up your mess.

    Beyond that it’s just a matter of being safe.


    Sent from my iPhone using Tapatalk

    Why is what I wrote "Bullshit " ?

    Not clear on the point you are trying to make in reference to what I wrote ?

    Or do you mean Claya doesn't care about safety but is more concerned about being "Busted" for something ?

    In France where I used to live it was pretty amazing the chemicals that you could buy (both in a good and bad way) - French law may have changed but seems their view was as private citizen if you bought really dangerous chemicals and accidently killed yourself in their use then that's on you / natural selection.

    Obviously liability is an overarching driver for most of these safety procedures even in small laboratories and Universities - but in the industrial environment I've always been very safety conscious as a lot of industrial accidents are a really shitty ways to die.

    So back to "Mystery alloy/ metal" ?

    So "Acid mix: 20%HF/20%Nitric/60%Diwater"

    And Claya already says he is working with concentrated Nitric and Sulphuric + has the appropriate safety equipment for that,

    So you are saying the 20% HF is going to nix whatever insurance he has when he dies of HF mishandling ? Or that doesn't matter ? (- and that should be his primary concern, like what @JCaroll is saying / advocates - Or are you saying Claya lacks the competence, diligence and resources to handle 20% HF ? Or should be using your friend for all this instead ?

    But you are saying that the alloy he is working with is a far greater liability all together ?

    And because you indicate that you know what metals he is working with in this case ? ~ Because of your friend that does this kind of stuff regularly handles super dangerous metals and therefore Claya must be doing the same ?

    I'm sure you know what you mean as you indicate that you know @Claya ?

    @Snowman are you saying @Claya should or should not attempt or even consider using 20% HF solution for the 1" x 2" specimen (in question) ? Because the alloy or metal is off the charts for toxicity ?

    Sounds like your "Thesis" is he should not even think about it and engage properly with your friend ?

    I'm not sure how old Claya is etc. / circumstances so seems you know or have a better handle on all that ?

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    Quote Originally Posted by snowman View Post
    No, he hasn’t...and if you know anything about that alloy, you should realize he’s not going to.
    Zirconium? It's like the third hit in google when you look up Nitric-Hydrofluoric pickling. If so, the paper from 1958 states that the removal of the work-hardened layer is key for corrosion resistance which makes more sense than "organic" contamination.


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