Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

Re: Apt quote on Corrosion

[Subject Prev][Subject Next][Thread Prev][Thread Next]
The term BRONZE in general means a copper alloy with tin as a major
alloying element.
Not to be confused with BRASS, which by age-old definition is a copper
alloy containing zinc
as the principal alloying element.     Some bronzes have evolved into a
family of copper alloys 
that may have other elements that tin as the major alloying element.  
Some bronzes have aluminum
as the major alloying element, manganese bronzes have zinc, phosphorous
bronze is used for
bearings that work at 250,000 rpm etc.    Bronze for bell castings in
addition to the main alloys has a few
additional "secret ingredinents" since ancient times.     "Bronze
disease" is a reaction of  cuprous chloride
and oxygen in a damp environment.    Once the reaction starts, cuprous
chloride turns to cupric chloride
and hydrocloric acid.     The so called diseaze turns in to small patches
of corrosion and it is distinguised 
by rough  light green spots on the bronze part.   The process can be
stopped by various chemical solutions.
In general bells come under the combination of bronze fatigue and bronze
disease as well as casting 
deficiencies.

There are a wide range of publications on the internet regarding this
issue.   A good one is Bronze Disease-
A review of some problems by David A. Scott (see JAIT 1990, Volume 29,
number 2, article 7, pp 193 to 206)

This is my $ 0.02  worth.  

djk




On Thu, 25 Jul 2002 14:08:29 -0700 "Nels Roselund, SE" <njineer(--nospam--at)att.net>
writes:
> Thanks Desi, for the enlightening discussion of corrosion.
> 
> Historic bells at one of the California Missions were cracked.  The 
> ringing
> of the bells sounded like the cleaning of the wheelbarrows.  It was 
> decided
> to recast them.  The material and configurations would be original, 
> but they
> would be newly cast bronze.
> 
> It was determined that they could not be recast because they had 
> suffered
> bronze disease, which I understand was a loss of one of the 
> component
> alloys.  Your descriptions of dealloying and of selective leaching 
> each
> seemed close to what I understood had happened to the bells.  Any 
> thoughts
> on bronze disease?
> 
> The final action was to use new bronze to cast replacement replicas, 
> and the
> old bells are to be put on display.
> 
> Nels Roselund
> Structural Engineer
> South San Gabriel, CA
> njineer(--nospam--at)att.net
> 
> 
> 
> ******* ****** ******* ******** ******* ******* ******* ***
> *   Read list FAQ at: http://www.seaint.org/list_FAQ.asp
> * 
> *   This email was sent to you via Structural Engineers 
> *   Association of Southern California (SEAOSC) server. To 
> *   subscribe (no fee) or UnSubscribe, please go to:
> *
> *   http://www.seaint.org/sealist1.asp
> *
> *   Questions to seaint-ad(--nospam--at)seaint.org. Remember, any email you 
> *   send to the list is public domain and may be re-posted 
> *   without your permission. Make sure you visit our web 
> *   site at: http://www.seaint.org 
> ******* ****** ****** ****** ******* ****** ****** ******** 


________________________________________________________________
GET INTERNET ACCESS FROM JUNO!
Juno offers FREE or PREMIUM Internet access for less!
Join Juno today!  For your FREE software, visit:
http://dl.www.juno.com/get/web/.

******* ****** ******* ******** ******* ******* ******* ***
*   Read list FAQ at: http://www.seaint.org/list_FAQ.asp
* 
*   This email was sent to you via Structural Engineers 
*   Association of Southern California (SEAOSC) server. To 
*   subscribe (no fee) or UnSubscribe, please go to:
*
*   http://www.seaint.org/sealist1.asp
*
*   Questions to seaint-ad(--nospam--at)seaint.org. Remember, any email you 
*   send to the list is public domain and may be re-posted 
*   without your permission. Make sure you visit our web 
*   site at: http://www.seaint.org 
******* ****** ****** ****** ******* ****** ****** ********