Page 58 - Glass-Technology International no. 3-2019

CHEMICAL TEMPERING

of tempered glass seems to other possibility is that of
be the trend at present for carrying out tests on the
a number of sectors, where tempered glass.
chemical tempered glass is
used for the external sheet GTI: Is there the possibility
and breaks up into very um for IG units; is chemi- due to its higher resistance of tempering only one part
small pieces when cut or cal tempering possible for to impact, and thermal or side of the glass sheet?
drilled. On the other hand, these thinner but large- tempering for the internal
chemically tempered glass, dimensioned glass sheets? sheet, where during impact Gianfranco Rivaroli: Since
which only has surface Gianfranco Rivaroli: Yes, the glass breaks up into the glass sheet is inserted
stress tension, can with- of course. And, consider- small pieces. into the salt solution verti-
stand these types of impacts ing other types of glass, cally, it’s quite difficult to
and is flexible, which means we have already supplied TECHNICAL ASPECTS do this, but it is possible.
that it can also be curved. a couple of plants for the OF THE PLANT In fact, a few years ago, I
In the architectural glass production of armoured GTI: How often do the salts developed a smaller special
sector, the advantage with glass for the automotive used for chemical temper- furnace for a university in
chemical tempering is that industry, which is now ing need to be replaced? the area of Tuscany, where
when the glass panes are requesting to reduce the they needed to temper only
assembled together they mass of the glass used in Gianfranco Rivaroli: In one of the surfaces of the
match perfectly, while with these special vehicles. chemical tempering, the glass to transmit electronic
thermal tempering, and the exchange takes place be- waves. More recently, a
consequent ‘waviness’ of Alessandro Rivaroli: Chemi- tween ions of potassium company in Modena de-
the glass sheets, this match- cal tempering used for ar- nitrate and sodium con- veloped their own furnaces
ing is not so perfect. And moured vehicles has now tained in the glass. The big- and bought the salts from
this means that lamination reached the level of ther- ger ions of potassium enter us to be used to temper
of these types of glass sheets mal tempering, because the glass, which releases the new types of vitreous-
becomes more complicated. the industry is combining sodium and compresses surface tiles.
these two types of tem- the glass surface. When So you can see that there
Roberta Cometti: It also be- pered glass. the salts reach a concentra- are endless applications for
come more expensive be- tion of sodium higher than the use of chemical tem-
cause you need to increase Roberta Cometti: There are 2 per cent, they can either pering.
the interlayer thickness, as in fact, requests for alter- be replaced or regenerated
well as using more pressure native solutions concern- by removing ‘old’ salts and
and more power. ing higher resistance and adding new salts. The lev- RCN Solutions Srl
smaller thicknesses. els of the salts obviously RCN Soluti
GTI: The architectural glass need to be constantly mon-
market is now starting to Gianfranco Rivaroli: The use itored.
look into the using of vacu- of these two different kinds One of the first companies
in Italy to use a plant of this
kind,replaced completely
after 10 years of work.
The need to regenerate the Via Marcatutto, 7
salts or replace them can 20080 Albairate (MI) - Italy
be seen in the quality of the Tel.: +39 - 02 - 94602434
glass produced – by plac- Fax: +39 - 02 - 94602244
ing some small samples E-mail: info@rcnsolutions.it
of glass inside the furnace www.rcnsolutions.it
and keeping a regular re-
cord of the parameters of
the tempered glass. The

E-mail: grivaro@tin.it

56 Glass-Technology International 3/2019