I got one "hit" on Google that is intriguing, using "Low Bo and magnetism" as the search phrase:
Magnetization Measurements of Antiferromagnetic SrCu2(BO3)2 using a VSM
Taeyjuana Curry,a under the direction of Prof. Yasumasa Takanob
a Department of Physics, Florida State University, Tallahassee, Florida 32304 b Department of Physics, University of Florida, Gainesville, Florida 32611
(July 28, 2004)
SrCu2(BO3)2 is a low-dimensional antiferromagnetic compound that has undergone many different magnetization studies; however, to date none have addressed the temperature dependence of the magnetization. Measuring this sample’s magnetism versus magnetic field at varying temperatures will provide insight into its quantum mechanical nature and help strengthen or refute the current theory. This experiment utilizes a vibrating sample magnetometer and DC magnet at the National High Magnetic Field Laboratory and covers a magnetic field range up to 30.1 T and a temperature range from 1.4 to 12.3 K. Our data show that the magnetization of the sample does in fact depend the temperature of the sample.
Post by scubadiverbob on Dec 21, 2006 14:16:38 GMT -8
I no longer have the set of Navy Dive Manuals; but, the type of paint might be in them (there were three volumns when I did the course (I did the course when out at sea on the USS Coral Sea then got transfered and never turned it in; it was very interesting reading (more than the CT rating manuals)).
Post by scubadiverbob on Dec 21, 2006 14:29:08 GMT -8
Another source for info that came to mind ... the Navy had Maintence Requirement Cards (MRC) for everything. If someone could find one (or get a copy of one from the Navy) the info on the paint type might just be there. Also, proceedures for cleaning and regular maintence would be in them (and if the paint had to be touched up ...) I was the Work Center Supervisor for my division (the Chief was supposed to be; but, never did his job); so, remembering what MRC's were might make me have nightmares for Christmas! (sounds like a cartoon/movie, huh?)
"Antiferromagnetic" does not mean "non-magnetic". I believe that antiferromagnetic (AFM) means the material simply doesn't follow the same magnetism patterns as a material with ferromagnetic properties, like iron and steel. As best as I can ascertain, the "amount" magnetism of chromium is temperature dependent in a way which differs from that of ferromagnetic materials. It may also be dependent on the temperature at which the metallic crystals were formed. That is going beyond my level of understanding, so if chromium is magnetic at temperatures involved in typical diving situations, then I would assume that this SrCu2(BO3)2 probably would be as well. Apparently, antiferromagnetism is a complicated science.
I would guess that maybe the regulators were initially blackened chemically (i.e. Black Oxide, as Dan said at the beginning), then maintained with paint. Just a wild guess, but it fits with what I've seen during military service. JAWAG
(The external portion of the gold-plated nozzles must have been painted black from the outset)
Last Edit: Dec 21, 2006 16:07:57 GMT -8 by duckbill
Silly humans, fins are for fish. Mammals use flippers.
I think from the chemical formula it does not have chromium in it, but rather copper. I read the chemical formula as stronium-di-copper boron-trioxide (probably wrongly, as poor as my chemistry is). As exotic as this stuff seems, this is unlikely to be the coating, no matter what the forumal says. I thought it was interesting though, that I got a hit like this using "low Bo and magnetism."
Scubadiverbob, I looked at the 1970 U.S. Navy Diving Manual, and although it pictures the Non-Magnetic DA Aquamaster for all its discussions of the regualator, it says nothing about the magnetic properties or coatings.
John C. Ratliff Diving since 1959, at age 13. Haven't stopped, and still enjoy getting wet.
John, I didn't mean to say that chromium was in the compound mentioned in the article. I was just noting that it did say that the compound is antiferromagnetic, as is chromium. I was just pointing out that if chromium is not used because of it's magnetic signature, this compound (SrCu2(BO3)2) probably wouldn't be used either (whatever it is).
Fun search, though. It came up because of the key words/letters used: " SrCu2(BO3)2 is a low-dimensional antiferromagnetic compound ................ this sample’s magnetism..." I wouldn't assume it means the compound is low in borate. Nonetheless, this compound is still magnetic.
Silly humans, fins are for fish. Mammals use flippers.
You guys are starting to sound like the "Professor" on Gilligan's Island. Great photos, John- thanks! After looking at many of my non-mag AquaMasters, I find that I still have more questions than answers. First of all, there appears to be 2 different symbol stampings for non- magnetic status on the regulator bodies. They look similar but one has an additional "arrow" through the symbol (see photos). Does anyone know if there is a different meaning between these two symbols? Secondly, I have found that many of the non-mag regs do have what appears to be chrome plated parts. At first , I just thought parts had been switched around but if you notice in the photo, there is a chrome plated body with the non-magnetic symbol. I also have cans with a chrome like finish underneath the black outer finish. I believe that these regulators stayed in service long after their use as a non-magnetic regulator was needed. They could have been used for training, inspection dives, or even for recreation. The maintenance people would replace parts as needed with whatever they had in stock and not use the very expensive gold plated parts or non-magnetic brass parts ( I realize that brass shouldn't be magnetic but the Navy used special brass for non-mag applications). And I also suspect that after the Navy stopped using two hose regulators, I'm sure these regs "drifted" off base and into private hands where they were still used and serviced for years. I have non-magnetic regulator bodies that have "chrome" and others that are just brass under the black coating. The same goes for the cans, yolks and yolk screws. I guess we need to find someone from the Navy who actually built or serviced these regulators to get to the bottom of this. Dan
Another mystery! I just found a gold plated Royal AquaMaster HP seat! I've never seen or even heard of a non-magnetic Royal AquaMaster. The other two parts, the pin support and AquaMaster spring block have a strange gold like plating but these two parts are not marked with the standard circular grove consistant with gold plated, non-magnetic parts.
Post by sea.explorer on Dec 22, 2006 19:43:29 GMT -8
I have one of the gold RAM seats as well. It had not occurred to me that it was gold until I saw Dan's post. It came out of a standard RAM as I recall so I'm not much help. Interesting. Is it possible that the seat is from a NM Conshelf? -Ryan
A couple thoughts: 1) After studying up on chromium, I couldn't find a source which came right out and said that chromium is (always) magnetic. Apparently, it's magnetic signature is temperature dependent, and may also depend on the temperature at which it was formed/deposited. Might it be possible to have a non-magnetic chrome plating? (I'd be willing to take back what I said about black over chrome being probable fakes if such is the case) Nickel, on the other hand, definitely has typical magnetic properies. Chrome CAN be applied to brass without a base of nickel plating, though. 2) There are other silver colored metal platings. Zinc and cadmium come to mind. Zinc would be grey from saltwater exposure, so I think that rules that one out. Then there is silver plating. I don't know what the magnetic signatures on these metals are.
My old electroplating boss had a then state-of-the-art 'Metal Analyzer'. It would use a radioactive source to non-intrusively and non-destructively analyze a metal or alloy, and would display the percentages of each elemental metal constituent. I think it would also tell what the thickness of a plating was as well. Wouldn't we love to have one of those to test these non-mag finishes on!!!
Thanks for sharing, Dan. I'm going off-line for a few days, but can't wait to come back to see what new information is here. Fun stuff!
Last Edit: Dec 22, 2006 21:00:35 GMT -8 by duckbill
Silly humans, fins are for fish. Mammals use flippers.
I have read and reread this series of posts with interest. I really never had an interest in non-magnetic regulators since I don't have one ......however...........these posts have made me wonder about the reasons for these type units in the first place.....or have I failed to understand the core of these conversations?
The USD regs are basicly brass correct? With just a few small tiny parts that are something other than brass. So why would the Navy use a non magnetic coat on these brass cans and accessories if these were not magnetic in the first place.....unless..........the chrome from that period was slightly magnetic...........
The small items inside would still attract a magnet up very close if they had a light coat of gold or what ever..........for example: My truck body is metal and covered with several coats of paint from the factory, however, a strong magnet will still stick to it............however........ the brass body of the reg should mask any small magnetic attractions to its small inner parts........there's the brass and a thick diaphgram between these small parts and the world.
So why did USD sell these regs to the Navy as anti-magnetic?
Was the Navy concerned about magnetic chrome back then? Is there some property of Chrome that sets off magnetic sensors from that period?
Or was the whole anti magnetic thing a sells come-on to buy USD goods.........or did the Navy require other than chrome regs to ease the worries of the divers who worked with Ordinance Disposal?
Could it be that USD double hose Non-magnetic regulators are nothing more than a "descriptive name" for non-chromed regulators? And there is really no physical or scientific reason for them labled as such.
Question . . . was the non-mag the ONLY one to have the non-machined hooka port? I have seen one recently on a display that was matte finish (I think) but definately did have the non-machined port.
No, I have a Navy USD two hose with the unmachined hooka port. It is very unusual as the regulator body thas the unmachined hookah port as found on the non mag Aqua Master but has the earlier DA Navy horseshoe and removeable volcano nozzel. It is not black but the finish is slightly different than the usual satin chrome. It has no lable. Sam Lecoco looked at it at Portage and comfirmed it as an authentic Navy regulator. So far it is the only one I have ever seen in that configuration.