precise melting point of euctetic solders? - Page 1
Forum section: electronics / general

author: ftransform
author_rank: Frequent Contributor
timestamp: March 14, 2013, 04:03:23 pm
content: Does anyone have a list of the precise melting points of various eutectic solders? Wikipedia has a list to 1 degree C, I would like a list which offers an order of magnitude more accuracy.I am interested in solders beyond the 33/67 tin lead type, for use in temperature calibrationrobrenz, help??

author: ftransform
author_rank: Frequent Contributor
timestamp: March 14, 2013, 04:26:28 pm
content: perhaps this is better left to other chemical compounds I don't know why I fixated on euctetic mixtures, I am sure there are pure compounds which offer a sharp melting point suitable for calibration. Stuck in a electronics mindset I suppose.Unless anyone has any objections?

author: G7PSK
author_rank: Super Contributor
timestamp: March 14, 2013, 04:29:41 pm
content: 63/37 alloy is the eutectic alloy of tin and lead and as far as I know the only lead tin alloy that goes from liquidus to solidus without any transitional stage.Phase diagram for lead alloys here.http://www.ami.ac.uk/courses/topics/0244_tsm/index.htmlhttp://books.google.co.uk/books?id=qvrq96gJFxIC&pg=PA484&lpg=PA484&dq=tin+lead+eutectic+solidus+temperature&source=bl&ots=EfcvWSoDa6&sig=QoVDh2lHWMd7V2IbBa-mvq0OFJU&hl=en&sa=X&ei=N_pBUcm5IObO0QXZh4CACg&ved=0CDoQ6AEwAQ#v=onepage&q=tin%20lead%20eutectic%20solidus%20temperature&f=falseTin silver copper eutectic alloy is the only lead free alloy that I know of the transition temperature of that is 217.2 deg C link here to a research paper.http://link.springer.com/article/10.1007%2Fs11661-000-0111-5?LI=true#page-1

author: ftransform
author_rank: Frequent Contributor
timestamp: March 14, 2013, 04:32:24 pm
content: Wikipedia has a list of solders which are listed as euctetic, there are like 10+http://en.wikipedia.org/wiki/Solder#Solder_alloysHowever this whole thread is moot because I am sure there non-metal compounds which could be used for calibration too, I was just stuck in a electronics mindset, so I fixated on metal alloys

author: G7PSK
author_rank: Super Contributor
timestamp: March 14, 2013, 04:40:26 pm
content: If you want a calibrated compound have a look at Templestik.http://www.tempil.com/products/tempilstik-original/They are a crayon that is made to melt at a specific temperature, used in the engineering industry for things like heat treatment and weld pre-heat etc. Made is a wide range of temperature and accurate to +/- one degree.Most metals have quite a wide range between molten and solid, I don't think that there is a list to the accuracy that you are looking for due to that.

author: ftransform
author_rank: Frequent Contributor
timestamp: March 14, 2013, 05:04:35 pm
content: Quote from: G7PSK on March 14, 2013, 04:40:26 pmI was thinking more along the lines of pure crystalline compounds like sucrose or whatnot.1 degree C is ok, but do you know of compounds *which could be bought on eBay or whatnot* that have melting points in the range of 0.1 degree or less? I see some listed on Google as having a melting point with a decimal in Fahrenheit but I believe that they take a rounded/imprecise value in Celsius and convert it to Fahrenheit, giving the illusion of resolution.

author: mzzj
author_rank: Super Contributor
timestamp: March 14, 2013, 06:00:37 pm
content: Did you plan to mix your own eutetics?I would stick with the pure compounds. ITS-90 temperature scale defining points would be good choices but spacing between these is sometimes impractical.Fixed points in temperature calibrations are high purity single compouns for a reason...http://www.its-90.com/fp7-sig.pdfhttp://en.wikipedia.org/wiki/International_Temperature_Scale_of_1990

author: SeanB
author_rank: Super Contributor
timestamp: March 14, 2013, 06:06:25 pm
content: Problem with this is that you need a very pure base metal to make the alloy from. Lead will have small amounts of silver, copper, antimony and other metals in it already when refined, and you will have to go through multiple extra stages to get a pure metal for making the alloy. Thus the range of melting points, as each batch will be slightly different. Offhand I cannot think of any phase transition that is both sharp, insensitive to environment and occurs easily other than using triple point cells as precise temperature points. Water is about the easiest to get in an ultra pure state.

author: ftransform
author_rank: Frequent Contributor
timestamp: March 14, 2013, 06:15:12 pm
content: well I just want crystalline compounds now, not mixtures of compounds.It is possible to purify certain metals using electrochemical processes but I think recrystalization of nonmetal compounds is an easier endevorI know silver can be purifed heavily through electrochemical process

author: mzzj
author_rank: Super Contributor
timestamp: March 14, 2013, 06:21:28 pm
content: Quote from: SeanB on March 14, 2013, 06:06:25 pmHigh purity Gallium is probably easiest option after water. Price is relatively low (if talking about other high purity materials) because lots of high purity Gallium is used and manufactured in the semiconductor industry.Nowadays there are some binary compound eutetics used for temperature calibration, but these are really exotic and expensive. Only used on temperatures beyond 1200 Cel as there is no suitable pure materials at these temps.http://www.npl.co.uk/temperature-humidity/products-services/supply-of-high-temperature-eutectic-fixed-points-for-calibration-of-thermocouples-1324Now, thats what I would like to have, Palladium-Carbon eutetic fixed point. Must be crazy expensive just because of the Palladium.

author: mzzj
author_rank: Super Contributor
timestamp: March 14, 2013, 10:30:40 pm
content: Quote from: ftransform on March 14, 2013, 04:03:23 pmMaybe we started this wrong way around. Do you have some specific application on your mind? Why not use fluid bath and calibrated Pt100 sensor as a reference?Melting point of water is easy, for 10$ you can get 0.002 K accuracy. Boiling point is also somewhat usable but you have to compensate for the local atmospheric pressure.