34
materials
➠
Chemical’s Exxtral performance polyolefins have been strength that provides the essential balance between
specified for the front and rear bumpers of the new stiffness and toughness required for bumper
Renault Laguna Coupe. Exxtral BMU131 performance applications. They offer a low coefficient of linear
polyolefin is being used for the front bumper, front grille thermal expansion (CLTE) for excellent dimensional
and headlight trim, and Exxtral BMU133 polyolefin for stability, too.
the rear bumper. According to Exxon, the Laguna Coupe application
“The main challenge in meeting Renault’s is an excellent example of collaboration between the
specifications was developing a specialty compound for automotive original equipment manufacturer (Renault),
the front bumper which provides outstanding fit and the Tier One supplier (Plastic Omnium), and the
finish,” said Samuel Deboos, automotive sales manager, specialty compound supplier to meet expectations
Europe, ExxonMobil Chemical. across the supply chain. The capabilities of the
Exxtral BMU131 polyolefin is a UV-stable grade Exxtral polyolefin grades were demonstrated at Plastic
exhibiting excellent aesthetics because of its broad Omnium’s design centre in Sainte-Julie near Lyon,
processing window that helps to eliminate large-part France.
injection molding challenges such as tiger stripes. “ExxonMobil Chemical’s portfolio of Exxtral
Requiring no mixing or blending at the moulding performance polyolefins is becoming increasingly
presses, Exxon says these ready-to-inject, fast-cycling popular with automotive designers and processors
grades can improve productivity and deliver cost- looking for new materials that offer opportunities
savings. to reduce weight and cost without sacrificing
Both grades are characterised by a novel impact performance,” added Deboos. v
Corrosion solutions ConferenCe
a
t the 7th international Corrosion metals such as tantalum, niobium,
solutions Conference (CsC09), 21st to zirconium, and titanium can offer superior
23rd september, 2009 in Park City, utah, corrosion resistance.
usa, metallurgists, fabricators, chemical of the reactive metals, only
and materials engineers will discuss commercially pure zirconium offers both
topics ranging from alloy development high resistance in concentrated inorganic
and plant engineering to fabrication, acidic chloride solutions and has sufficient
failure analysis, and much more. strength to be approved for construction
Conference sessions are tailored to of welded pressure vessels.
chemical processing, oil and gas, material although zirconium is generally
selection, fabrication advances, and other successful in these environments,
challenging processing environments. stress-corrosion cracking (sCC) and
the following abstract provides a glimpse intergranular attack (iGa), can occur
of the papers being presented at this in hydrochloric acid concentrations
year’s event >20 per cent and pitting can occur in
No signs of attack.
although few metals can survive concentrations <20 per cent. several
chemical environments with high factors are thought to affect the corrosion surface conditioning methods for the
concentrations of chloride ions; reactive resistance of Zr702 in concentrated use of zirconium in hydrochloric acid
chlorides including: environments.
v Presence of oxidizing ions in solution,
Both images are from the apex of a
eg ferric ion (fe
3+
) or cupric ion (Cu
2+
).
u-bend in the parent metal. left: sample
v surface roughness of the zirconium.
shows signs of severe intergranular
v internal stresses in the zirconium.
attack (iGa). large voids are from where
v Post-weld heat treatment.
the attack has completely dislodged the
v thickness of passive oxide film.
grains.
v impurity levels of base material, ie fe,
Bottom of photo shows a deep
ni, Cr, and sn.
penetrating crack, possibly the result of
stress Corrosion Cracking (sCC).
Zirconium’s performance in right: sample shows no signs of
hydrochloric acid can be dramatically attack. surface oxide is intact. v
improved by conditioning its surfaces
through a variety of different processes.
enter 34 or ✔ at www.engineerlive.com/ece
this paper will explore the results of ATI Wah Chang is based in Albany, OR,
Signs of intergranular attack.. testing intended to determine the best USA. www.wahchang.com
www.engineerlive.com
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