Lessons on Alloys, Amalgams, and Pleonasms (1) 
Author Message
 Lessons on Alloys, Amalgams, and Pleonasms (1)

Keith P. Walsh is spreading drivel again (August 25, 2007). As usual
he is confused, and he may be confusing readers of both the
sci.med.dentistry and sci.materials newsgroups. He needs to take some
lessons rather than try to give them.

Point 1: The technical definition for an alloy (a noun describing a
material)

The Merriam-Webster OnLine Dictionary defines an alloy as:
"a substance composed of two or more metals or of a metal and a
nonmetal intimately united usually by being fused together and
dissolving in each other when molten". Note the qualification
"usually" to describe the process of melting.

The Random House Unabridged Dictionary has a similar definition: "a
substance composed of two or more metals, or of a metal or metals with
a nonmetal, intimately mixed, as by fusion or electrodeposition".

Mr. Walsh prefers to use a narrower, crankier definition that:
"An alloy is formed by raising each of the constituent metals to be
alloyed to a temperature above its melting point, mixing the metal
constituents thoroughly whilst they are all in their molten states,
and allowing the mixture to solidify by cooling at a controlled rate."

By Mr. Walsh's definition an amalgam is not a "true alloy", since the
process used for making it (transient liquid phase sintering) does not
involve complete melting.

All the above definitions complicate matters by trying to describe
both a material and the process of mixing used to make it.

A sensible place to find a technical definition for an alloy is in the
ASM Materials Engineering Dictionary, which was published in 1992 by
ASM International (The Materials Information Society). This dictionary
defines an alloy as: "A substance having metallic properties and being
composed of two or more chemical elements of which at least one is a
metal". This definition simply describes an alloy as a material,
without limiting the process used to make it.

The definition comes from the ASM Metals Handbook. It is right out of
the Glossary of Metallurgical Terms at the beginning of the Metals
Handbook, Desk Edition  (page 1.3 of the first 1985 edition, or page 5
of the second 1998 edition).

The exact same definition appeared fifty years earlier on page 1 in
the Definitions of Metallurgical Terms at the beginning of the 1948
edition of the Metals Handbook (published by the American Society for
Metals, the predecessor of ASM International).

A similar definition also appears earlier on page 3 in the 1939
edition of the Metals Handbook, which defines an alloy as: "a mixture
with metallic properties composed of two or more elements of which at
least one is a metal".

Similar definitions appear in textbooks. One example is Materials
Science and Engineering: An Introduction, by William D. Callister, Jr.
The glossary on page 810 of the fourth edition, John Wiley & Sons,
1997 defines an alloy simply as:
"a metallic substance that is composed of two or more elements".

The Oxford English Dictionary (1989 edition) also defines an alloy
broadly as: "a mixture of metals; a metallic compound, an amalgam."

I believe that the time-tested (almost sixty year old) Metals Handbook
definition is a sensible description for what an alloy is.

Pittsburgh Pete

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Sun, 14 Feb 2010 21:55:37 GMT
 Lessons on Alloys, Amalgams, and Pleonasms (1)

Quote:

> The Oxford English Dictionary (1989 edition) also defines an alloy
> broadly as: "a mixture of metals; a metallic compound, an amalgam."

> I believe that the time-tested (almost sixty year old) Metals Handbook
> definition is a sensible description for what an alloy is.

So it's OK for me to call those mixtures of metals made with liquid
gallium "amalgams" then Pete?

Keith P Walsh



Mon, 15 Feb 2010 01:12:12 GMT
 Lessons on Alloys, Amalgams, and Pleonasms (1)

Quote:

> The Oxford English Dictionary (1989 edition) also defines an alloy
> broadly as: "a mixture of metals; a metallic compound, an amalgam."

> I believe that the time-tested (almost sixty year old) Metals Handbook
> definition is a sensible description for what an alloy is.

> Pittsburgh Pete

Hey Pittsburgh Pete where are you?

Don't go all shy on us now - things are just getting interesting.

I've found some more people who call gallium amalgams "gallium
amalgams". And they mean "gallium amalgams with no mercury in them".

It's Giles Humpston and David M Jacobson in their book, "Principles of
Soldering", published by ASM International (April 2004) and endorsed
by The Materials Information Society.

You can read it yourself by following this link:

http://books.google.com/books?id=cQ6khQScBF4C&pg=PA103&dq=%22gallium+...

The parts which are of interest to us are:

Page 115 - Section 5.4.1 - Amalgams Based on Mercury

Page 116 - Section 5.4.2 - Amalgams Based on Gallium

"Gallium melts at 29 deg C and is therefore a potential base for
formulating very low-process-temperature amalgams without the toxic
hazard associated with mercury"

(Note, there's no mercury in these amalgams.)

Page 117 - Section 5.4.3 - Amalgams Based on Indium

"Indium is another liquid metal that can be considered as a base for
amalgam systems. "

(There's no mercury in these amalgams either.)

So I think this just about settles it. The term "mercury amalgam" is
NOT a pleonasm, because on its own the word "amalgam" is not
sufficient to distinguish between mercury amalgams, gallium amalgams
and indium amalgams.

Maybe the lesson to learn is that we shouldn't so easily allow
ourselves to be misled by dentists who were misled by their professors
in dental schools.

Keith P Walsh



Tue, 16 Feb 2010 02:55:04 GMT
 Lessons on Alloys, Amalgams, and Pleonasms (1)


Quote:

> > The Oxford English Dictionary (1989 edition) also defines an alloy
> > broadly as: "a mixture of metals; a metallic compound, an amalgam."

> > I believe that the time-tested (almost sixty year old) Metals Handbook
> > definition is a sensible description for what an alloy is.

> > Pittsburgh Pete

> Hey Pittsburgh Pete where are you?

> Don't go all shy on us now - things are just getting interesting.

> I've found some more people who call gallium amalgams "gallium
> amalgams". And they mean "gallium amalgams with no mercury in them".

> It's Giles Humpston and David M Jacobson in their book, "Principles of
> Soldering", published by ASM International (April 2004) and endorsed
> by The Materials Information Society.

> You can read it yourself by following this link:

> http://books.google.com/books?id=cQ6khQScBF4C&pg=PA103&dq=%22gallium+...

> The parts which are of interest to us are:

> Page 115 - Section 5.4.1 - Amalgams Based on Mercury

> Page 116 - Section 5.4.2 - Amalgams Based on Gallium

> "Gallium melts at 29 deg C and is therefore a potential base for
> formulating very low-process-temperature amalgams without the toxic
> hazard associated with mercury"

> (Note, there's no mercury in these amalgams.)

> Page 117 - Section 5.4.3 - Amalgams Based on Indium

> "Indium is another liquid metal that can be considered as a base for
> amalgam systems. "

> (There's no mercury in these amalgams either.)

> So I think this just about settles it. The term "mercury amalgam" is
> NOT a pleonasm, because on its own the word "amalgam" is not
> sufficient to distinguish between mercury amalgams, gallium amalgams
> and indium amalgams.

> Maybe the lesson to learn is that we shouldn't so easily allow
> ourselves to be misled by dentists who were misled by their professors
> in dental schools.

> Keith P Walsh

Well!

It looks like somebody finally led the troll off of his jihad about
thermoelectric current, if only for  a while.

I guess that usenet newsgroups can still be fun to read..

Graybald



Tue, 16 Feb 2010 04:05:01 GMT
 Lessons on Alloys, Amalgams, and Pleonasms (1)
The repeated repeatedly deleted.


Fri, 19 Feb 2010 15:37:10 GMT
 Lessons on Alloys, Amalgams, and Pleonasms (1)

Quote:
> The repeated repeatedly deleted.

that's rich coming from you


Sun, 21 Feb 2010 02:33:19 GMT
 
 [ 6 post ] 

 Relevant Pages 

1. Lessons on Alloys, Amalgams, and Pleonasms (2)

2. Lessons on Alloys, Amalgams, and Pleonasms (3)

3. #2 ~ FDA: Dental Devices: Classification of Encapsulated Amalgam Alloy and Dental Mercury and Reclassification of Dental Mercury; Issuance of Special Controls for Amalgam Alloy

4. #1 ~ FDA: Dental Devices: Classification of Encapsulated Amalgam Alloy and Dental Mercury and Reclassification of Dental Mercury; Issuance of Special Controls for Amalgam Alloy

5. #3 ~ FDA: Dental Devices: Classification of Encapsulated Amalgam Alloy and Dental Mercury and Reclassification of Dental Mercury; Issuance of Special Controls for Amalgam Alloy

6. Amalgam is not a true alloy

7. A Lesson On Amalgams

8. The Difference Between an Alloy and an Amalgam - It's Thermoelectric!

9. {HELP} burn out(non precious alloy)

10. Alloy content

11. Resource for dental alloys used for castings

12. Alloy Online -- Jan should not go near it!


 
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