Chemical properties (GG17 GLASS)
The chemical resistance of CORDIAL® exceeds that
of most metals and other materials even where long exposure times
and temperatures in excess of 100¡ãC are involved. Exposure to
water and acids only results in the leaching out of very small
amounts of mainly univalent ions from the glass. The resultant
very thin layer of silica with few pores in it that is formed
on the surface inhibits further attack. CORDIAL ®
has very high resistance to attack by water, neutral and acid
salt solutions, strong acids and mixtures thereof, and also chlorine,
bromine, iodine and organic substances. Only hydrofluoric acid,
solutions containing fluorides such as ammonium fluoride, very
hot phosphoric acid and strongly alkaline solutions attack the
surface of the glass to an increasing extent at higher concentrations
in Wt.Mg/M 2
|Water distilled at 100¡ãC
|Water vapour steam at 121¡ãC
|80% H2SO4 at 130¡ã C
|Alkali 1 N Soln of Na2CO3 Boiling
Physical properties (GG17 GLASS)
A feature of CORDIAL®,
which makes it especially suitable for laboratory use, is its
thermal resistance, the following individual properties being
of particular validity.
Temperature resistance on being heated up and thermal shock resistance
maximum permissible operating temperature for CORDIAL ®
is 500¡ãC. Above a temperature of 525¡ãC the glass begins to ¡°soften¡±,
i.e. it begins to change from the solid state to the viscous state.
CORDIAL ® not only has a high resistance to chemical
attack but it also has a very low coefficient of expansion and,
as a result, a high resistance to thermal shock. This thermal
shock resistance exceeds that of ordinary glass by a factor of
three. That means that any change from hot to cold can be handled
very well. The linear coefficient of expansion of CORDIAL
® (20/300¡ãC) is 3.3 ¡¤ 10-6/K. That means that for an
increase in temperature of 1000 C0 the
glass only expands by 3.3 ¡¤ 10-6 relative units of length. That
is so little that hardly any stress is set up in the glass and
the glass does not break when, for example, boiling water is poured
Temperature resistance at freezing temperatures
CORDIAL ® can be cooled down to the maximum possible
negative temperature. That means that CORDIAL ®
is also suitable for use in liquid air (approx. -192¡ãC). In general
DURAN® products are recommended for use down to
-70¡ãC. When cooling down and thawing care must be taken to avoid
a temperature difference of more than 100K. When freezing substances
in such items as bottles or test tubes, the container should only
be filled to a maximum of ¾ of its capacity and it must
be frozen on the slant (45¡ãC).
Use in the microwave
CORDIAL ® is suitable for use in microwaves (under
Percentage by weight
As the thermal expansion coefficient of Borosilicate glass is low,
the thermal stress is under a given temperature gradient are consequently
low and the glass can withstand higher temperature gradients and
also sudden temperature changes/thermal shocks.
of Linear Expansion
x 10 ¨C70 C
conductivity (Cal/Cm3 /C/Sec)
The "Strain Point" should be regarded as the maximum
safe operating temperature of CORDIAL
When heated above 500¡ã C the glass may acquire permanent stresses
Optical properties (GG17 GLASS)
CORDIAL® exhibits no significant absorption in
the visible range of the spectrum(GG17 GLASS). This means that
the appearance of CORDIAL ® is clear and colorless.
In the approx. 310-2200nm range of the spectrum the absorption
of CORDIAL ® is negligibly low. For work with light-sensitive
substances the surface of the glass can be tinted brown with a
diffusion color. This results in strong absorption in the short-wave
region. For work with light-sensitive substances the surface of
the glass can be tinted brown with a diffusion color. This results
in strong absorption in the short-wave region. The absorption
margin for tinted glass is at about 500nm.
In photochemical processes the light transmission of CORDIAL
® in the ultraviolet range is of particular importance.
The degree of transmission in the UV range shows that photochemical
reactions, for example chlorinations and sulfochlorinations, can
be carried out. The chlorine molecule absorbs in the 280¡ª400nm
range and thus serves as a carrier of the radiation energy.
All illustration is supplied by YANCHENG CORDIAL CO., LTD.
All rights reserved.