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QS8 Connector Issues / Plating onto Nichrome

Q. These QS8 plugs only have a 5 ohm resistor used for the anti-spark function and it's not high enough for using higher voltage and the 5 ohm resistor burns out; would plating with high phosphorous electroless nickel increase the resistance enough to get the anti-spark contact up to 10 ohms?

Hummina/ John murphy
- Sausalito California
September 11, 2022

A. Hi John. I could be misunderstanding because I only learned what a QS8 plug is about 10 minutes ago. but my understanding is that it deters sparks by presenting 5 ohms of resistance as the contacts come together, but once they're fully engaged the resistor is bypassed.

If your voltage is high enough that it burns out the resistor, it seems that hacking the QS8 with a higher wattage resistor or a 10 OHM unit would be more practical than increasing the contact resistance; if you succeeded in introducing a poor contact situation where the resistance across them was 5 ohms while running, you would waste a lot of energy and likely overheat the contacts.

Luck & Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha - Pine Beach, New Jersey

Q. Thanks for getting back to me.

The plug has two bands on one side of the plug so when you push them together it contacts the first band, with resistor, then pushes through to the more conductive contact. I would paint the second big contact with something so it wouldn't get plated and only the first band would get plated and hopefully increase its electrical resistance. A rare want of increasing resistance.

Humminashadeeba, John, , murphy [returning]
- Sausalito California
September 12, 2022

A. Hi John. I don't think it's a practical strategy. Typical contact resistances are measured in micro-ohms rather that milli-ohms let alone ohms. Even with electroless nickel coating, the resistance across the connector will probably be but a few micro-ohms.

Luck & Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha - Pine Beach, New Jersey

⇩ Closely related postings, oldest first ⇩

We use phosphor bronze grade 2- code IS-7814 (indian standard) in contact with nichrome wire to sense the variable resistance of nichrome winding plate. We tried to use Ni plated bronze in contact with nichrome wire. We faced the problem that is it looses its electrical continuity anywhere in that winding plate while visually it is in contact with that plate kindly tell us the possible reason thanks.

Aviansh [last name deleted for privacy by Editor]
Industrial Electronics - Kanpur, UP , India

A. Nickel tarnishes, such that it is suitable for some electrical applications and not for others. For very low voltage situations and where you need very reliable very low resistance contact, you need precious metal plating. Look at a cell-phone, video game, or other mass market item and you'll see nickel or electroless nickel on the charging circuit contacts but gold on the digital contacts.

Ted Mooney,
Ted Mooney, P.E.
Striving to live Aloha - Pine Beach, New Jersey

How to silver plate nichrome

Q. How can I do silver plating on nichrome based metal plate?

sandip panchal
shree chamunda silverplating works - Ahmedabad, gujarat, India
July 7, 2018

A. Hi Sandip. As a silver plater you already recognize the several steps involved in silver plating, and you already recognize the various things that can go wrong or cause difficulties, such as poor adhesion, poor coloration, poor throwing power with heavy thicknesses in one area and low thicknesses in another, etc. What problems are you having and what are you trying to silver plate -- nichrome wire, strip, or individual items? Are you brush plating, rack plating, or barrel plating? Can you use a nickel strike? Are you using conventional cyanide silver? Do you do cyanide copper under it?

Nichrome is deliberately of high resistance, so it is possible that its resistance is causing you problems with your racking or barreling arrangements. It is difficult to activate, like stainless steel. It is also difficult to etch.

Please be specific about what you've tried and what specific difficulties you are encountering. Thanks!


pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha - Pine Beach, New Jersey
July 2018

Q. Sir, I tried to do copper plating on it but the coating is never sustained … I even used sodium cyanide for doing silver plating, but same thing happens again. The layer is never sustained on the metal.
So my biggest question is: is electroplating on nichrome possible or not?
And I've also done everything … I used copper sulphate, sodium cyanide, barrel plating …

sandip panchal [returning]
shree chamunda silverplating works - ahmedabad, gujarat, India
July 13, 2018

A. Hi again. I saw a research paper where nickel was plated onto nichrome from a Watts bath, although I suspect that more reliable adhesion can be achieved by using a Wood's Nickel Strike first (it is used both on stainless steel and pure nickel, so I don't have a good reason to think it wouldn't work on nichrome). The nickel strike could be followed by copper plating and then silver strike and silver plating if desired.

Unfortunately we are having a little communication problem: I''ve been asking exactly what happens when you are try to plate this, but your answer is that plating is "never sustained" and I just don't know what that means :-)
it never starts ... or it stops after a few millionths of an inch thickness --- or it deposits okay but peels off ... or what. Thanks.

Luck & Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha - Pine Beach, New Jersey

October 1, 2021

Q. Hi. I am an engineer working on an inhalation device and biocompatability.
I have a nichrome heating wire (it's 80% nickel and 20% chromium). It works well for heating and vaporizing.
Its resistivity is 125 X 10^-8 ohm-cm, which makes for a high resistance heater.
The problem is that I need to block the nickel from leaching out for bio-compatibility.
So I was thinking that I would plate the nichrome wire.
However, I need the coating material to have a higher resistivity than the nichrome for it to work properly.
I have found that Manganese, Germanium, carbon and ceramic would have a higher resistivity, but I'm not sure that these can be used for plating.
Can someone help on this?

Thank you.

Dani Freeman
- Woodland Hills, California

A. Hi Dani. Manganese & manganese alloys can be electrodeposited, although it's not easy (see thread 6524 and thread 28617). To my knowledge germanium, carbon and ceramics are not electrodepositable.

The highest resistance common plating that I am familiar with is high phosphorous electroless nickel at a resistivity of 110-120 X 10^-6 ohm-cm, and it is very corrosion resistant ... and I'm not sure that it would leach significant nickel.

You might want to double-check the value you submitted for nichrome because in the couple of sources where I looked, they reported values very close to high phosphorous electroless nickel plating. I suspect it might have been on charts as 125 X10^-8 ohm-m or 125 x 10^-6 ohm-cm and the units or the powers of 10 got transposed.

Luck & Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha - Pine Beach, New Jersey
October 2021

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