# electric motor points



## kamranashraf (Dec 12, 2009)

i recently purchase container load electric motors i open one and found 6 pointers 4 are about 4 to 6mm diameter and 2 mm thick and tow are about half cm diameter and 2mm thick i put them in 70% nitric and after tow days they was as is only copper which is attched as a very small amount disolve and solution color is blue so i put it on hot plate after 15 minuts one small point disolve but only 80% the dissolved point now look like very whitish others 5 are as is what are these poointers every one ever recycle them forgive me if anyone cant understand because i also donot know how to describe them soon i ,ll take some pictures,


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## Anonymous (Dec 12, 2009)

Mostly they are bronze with graphite or graphite, there may be other types, but every motor I have taken appart was one of the two.


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## shadybear (Dec 12, 2009)

70% nitric sounds high shouldn't that be diluted to work


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## teclu (Dec 12, 2009)

I had some types of russian electric micro-motors(centrifugal for example)with contacts for coupling and decoupling of movement, these contacts are PtIr10 or PdIr20, 1,12 grams or 0,98 grams of alloy/1piece of electrical micro-motor(6 contacts).If the alloy element is Ir then just in AR you can test these points, PdIr20 dissolves quickly in heated AR, the colour is dark reddish brown,.... and PtIr10 not dissolve in AR.

teclu


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## kamranashraf (Dec 14, 2009)

i finally decide to dip them into AR i was waiting for three days but the points are as is.first i dip them into 75ml nitric the nitric eat the copper which is attached with points and color was blue now i add HCL and soloution quantity is 250ml the points are melting fastelly and solution color is yellow i am try to upload pictures but i donot know why isnt its working,there is small red lins are rising in the solution and going up after 15 minuts the solution color is solid yellow is there any presiouce metal expected or should i check through stannouse CL, ?


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## lazersteve (Dec 14, 2009)

Always rely on stannous for testing as the color of the solution is not a reliable indicator.

Steve


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## shadybear (Dec 14, 2009)

kamranashraf said:


> i finally decide to dip them into AR i was waiting for three days but the points are as is.first i dip them into 75ml nitric the nitric eat the copper which is attached with points and color was blue now i add HCL and soloution quantity is 250ml the points are melting fastelly and solution color is yellow i am try to upload pictures but i donot know why isnt its working,there is small red lins are rising in the solution and going up after 15 minuts the solution color is solid yellow is there any presiouce metal expected or should i check through stannouse CL, ?


Why would you add HCL to your Nitric After it was contaminated with copper?


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## kamranashraf (Dec 14, 2009)

the quantity of the copper was very low like needle point and the color was very lihgt blue is this a mistake to add hcl into nitric then how to make aqua regia ?may be the yellow color because of copper but copper amount was very low i donot think its because of copper i have seen the points are disolving and color beaing yellow also reddish lines are rising i ,ll check through stanouse can any one guide me how to check with stanouse Cl?


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## butcher (Dec 15, 2009)

are these actually points, or are you talking about DC motor brushes?


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## kamranashraf (Dec 15, 2009)

can any one pm me his email becaus my window need to reinstall its dosent uploading any thing an my internet speed is slow so i ,ll send him the pictures ans he can upload them,the situation is i dip them the points yesterday 9pm in AR and in morning troday 10pm all yellow powder is settle down and now slution color is brown i didnot heat up my AR so may be thats why the brown powder isnt disolve i need matlic tin to check through so i ,ll get it soon,and show the results,what is the yellow powder which isnt disolved in cold AR may be its reddish brown i need some one to show my pictures to experts thanks


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## kamranashraf (Dec 15, 2009)

here is the last picture


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## kamranashraf (Dec 15, 2009)

thank god atleast i am able to upload last picture the picture slution colour is redish brown and all yellow posder is setle down , here is first picture which is disolving the points the second picture you can see the points


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## kamranashraf (Dec 15, 2009)

here is the second picture where you can see the points who are melting fastely


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## kamranashraf (Dec 15, 2009)

here is the powder look like white but it is yellow very solid yellow,


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## kamranashraf (Dec 17, 2009)

butcher i ,ll take some pictures and show you,teclu pleas guied me is i simply take a little sloution an put small peice of tin then tak on burner or there is diffrent mathod to check for any PM,i am stuck here untill any one guide me what i hav to do next,
thanks


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## butcher (Dec 18, 2009)

are you asking about the stannous chloride test?
tin (95% tin solder will work) disolved with some heat in hydrochloric acid (HCL) (muratic), a drop of your solution you wish to test then a drop of the stannous chloride, some use paper or qtip, some use a white spot plate, gold Would be violet colored spot.

there is alot of really good information on stannous chloride making it and testing, written here on this forum just for you to learn, all you will have to do is read it.


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## teclu (Dec 19, 2009)

kamranashraf Hi,



I can not pronounce about your solutions, did you dissolved the contacts points and lamellas together? Can you put an picture with contacts points and lamellas?
Take few contacts points(without lamellas) first tested these points with a magnet, then put in HNO3 50/50(1ml water and 1ml HNO3 70%), if there is no reaction next is AR(4ml HCL32%+ 1ml HNO3 70% dissolve aprox.1 gram of metal).
If in HNO3 you have reaction and the color tends to yellow to brown the Pd is present in alloy.
If you have Pt or W you can dissolve the points in hot AR but then you must test with stannous chloride, please take the steve and butcher advices for testing steps.

teclu


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