R. Suihkonen, J. Perolainen, M. Lindgren, K. Valtonen, N. Ojala, E. Sarlin, J. Vuorinen: Erosion wear of glass fibre reinforced vinyl ester, Nordtrib 2014, Aarhus 10.-13.6.2014. Presentation by Kati Valtonen. Glass fibre reinforced vinyl ester composites are widely used in tanks, piping, ducts, and fans in demanding applications, such as waste water treatment plants,chemical processing, and pulp and paper manufacturing due to their excellent chemical resistance and mechanical performance. In addition to corrosive environments, materials are typically exposed to erosion wear and high temperatures (close to 100°C) in many hydrometallurgical processes. However, there is limited understanding on the erosion wear of vinyl ester based composites and, therefore, knowledge should be gained on this field in order to evaluate their long-term behaviour and to optimise the maintenance intervals of different structures in various wear conditions. This study evaluates the slurry-erosion wear of glass fibre reinforced vinyl ester composites (VE-FRP) using a high speed slurry-pot type wear tester. The wear rates of VE-FRP were compared using different abrasives, namely quartz, chromite, ore, concentrate, and tailings. Furthermore, the effect of abrasive particle size and slurry concentration on the VE-FRP wear was studied. The erosion wear results of VE-FRP were compared to different rubbers, such as natural rubber (NR) and bromobutyl rubber (BIIR) as well as to few common thermoplastics, such as polypropylene (PP) and polyvinyl chloride (PVC), which are potential sensor, gauge, lining, and other wear resistant part materials in hydrometallurgical applications. The results demonstrated that coarse quartz produced the largest wear rates on VE-FRP samples, while the concentrate showed the lowest wear. Minor changes in the abrasive particle size had no effect on the wear results, only when the particle size was markedly raised, the wear started to increase. When comparing the wear rates of different materials, it was concluded that with all abrasive types, tested rubbers and thermoplastics had lower wear rates than VE-FRP.

1. EROSION WEAR OF GLASS FIBRE
REINFORCED VINYL ESTER
Reija Suihkonen, Juuso Perolainen, Mari Lindgren*,
Kati Valtonen, Niko Ojala, Essi Sarlin, Jyrki Vuorinen
Tampere University of Technology
Department of Materials Science
Tampere Wear Center
*Outotec Research Center
The 16th Nordic Symposium on Tribology – NORDTRIB 2014
10th-13th June 2014, Aarhus, Denmark

2. Department of Materials Science
Internationally high-level know-how on all materials based on
strong interdisciplinary basic research

3. Background of the study
• Glass fibre reinforced vinyl ester
composites are widely used e.g. in tanks,
piping, and ducts
– Waste water treatment plants
– Chemical processing
– Pulp and paper manufacturing
• Demanding environments:
– Corrosive (e.g. 5% H2SO4)
– Elevated temperatures (close to 100°C)
– Erosive wear
• Wear mechanisms in fibre reinforced
polymers more complicated than in
polymers and metals
– Different material components and their
interfaces
– Several wear types at the same time (e.g.
abrasion, fatigue, plastic deformation, melting)
Outotec OKTOP® Reactors

4. High speed slurry-pot wear tester
• Comparison of abrasives and their
effects on the wear of different materials
• Consists of a motor-run rotating shaft to
which the sample holders are attached in
four different levels
• Rotating speeds up to 20 m/s possible
• Test parameters:
– 8 samples were tested simultaneously
– Wear varies in different levels ® samples
are rotated through all sample levels
– Testing time 4 x 10 min
– Tested samples (size 35 mm x 35 mm)
were attached to the sample holders by
pressing them between two steel frames
– Rotation speed 1400 rpm (12.5 m/s at the
tip of the blade)
– Slurry consisted of 10 l tap water and
abrasive material (0.5, 1.0, or 3.0 kg).

5. Test materials and abrasives
• Glass fibre reinforced vinyl ester composite
– Epoxy vinyl ester resin (Derakane Momentum 411-350)
– 6 layers of chopped E-glass mat (300 g/m2) & C-glass surface mats (26 g/m2)
– Manufactured laminate size 1000 mm x 1000 mm, thickness roughly 3 mm
– Post cured in 80°C for four hours
– Sample edges were sealed with vinyl ester resin
• Other polymers for comparison:
– Natural rubber (NR)
– Bromobutyl rubber (BIIR)
– Polypropylene (PP)
– Polyvinyl chloride (PVC)
• Five different types of abrasives:
– Quartz (four different particle sizes)
– Chromite (fine and coarse)
– Concentrate
– Ore
– Tailings
.

6. Abrasive
characterization
Quartz (125-185 µm)
Quartz (100-600 µm)
Chromite (fine)
Chromite (coarse)
Concentrate
Ore
Tailings

7. Small variations in quartz particle size
did not have a marked effect on the
weight loss of fibre reinforced vinyl ester
• The highest erosion rate was obtained with coarse quartz with large (100 -
600 µm) particle size
• Coarse chromite (D50 57 µm) was more abrasive than quartz with larger
particle size (D50 80-119 µm)
1.0 kg, 40 min, 1400 rpm
Large, round holes and long,
wide, and randomly oriented
grooves

8. Erosion rate of fibre reinforced vinyl
ester depend markedly on the kinetic
energy of the impacting abrasive material
• Abrasives with smaller particle size, such as concentrate and ore, were
clearly less erosive
• Tailings, with large average particle size but lamellar structure, caused only
moderate erosion rates
• VE-FRP had the most
modest erosion resistance
of the tested materials
– Brittle fibres in fibre
reinforced vinyl ester
• Polypropylene had the
lowest wear rates
– Thermoplastic materials
exhibit ductile behaviour
• Rubbers can dissipate the
kinetic energy of the
abrasives
1.0 kg, 40 min, 1400 rpm

9. 0
0.5
1
1.5
0 1 2 3
VE-FRPweightloss(wt.%)
Amount of abrasive in the slurry (kg)
Quartz (100-600 µm)
Quartz (125-185 µm)
Tailings
Effect of abrasive concentration on
erosion wear results
• No change in the weight
loss when the amount of
abrasive was raised from
0.5 to 1.0 kg
• When the abrasive
content in the slurry was
raised to 3.0 kg, a small
increase in the VE-FRP
weight loss can be
observed
– high variation in the
results with 3.0 kg of
quartz (100-600 mm)
40 min, 1400 rpm

10. Wear surface
characterization
• The lower wear, rate the narrower and
shallower are the grooves created in the
sample surface
– VE-FRP wear surfaces rather smooth after
the erosion test with ore and concentrate
– Quartz (125-185 μm) that produced lower
wear than coarse quartz (100-600 μm)
causes minor damage to the surface
• Quartz (100-600 μm) causes large, round
holes as well as long, wide, and
randomly oriented grooves to the VE-
FRP surface
– Severe matrix removal followed by fibre
breaking and debonding
– Not only single fibres but fibre bundles
exposed and partially detached from the
matrix.
10
Quartz (125-185 µm)
Quartz (100-600 µm)
Concentrate

11. Erosion process of
glass fibre reinforced
vinyl ester
1. Local removal of the matrix material
– Creation of small holes, craters, and
exposed fibres
2. Abrasive particles bombard the
exposed fibre surfaces
– Generation of small scratches and
pits
3. Fibre fragmentation into several small
parts
4. Detachment of fibres from the matrix
– Creation of distinctive, deep tracks
11
2
3
4

12. Conclusions
• The erosion wear of glass fibre reinforced vinyl ester depends highly
on the abrasive type, size, hardness, and its kinetic energy
• The coarse quartz with the highest kinetic energy produced the
highest erosion wear
– Small variations in quartz particle size did not have a significant effect
on the erosion wear of the glass fibre reinforced vinyl ester
• When the erosiveness of finer particles was compared, the wear rate
caused by hard chromite was the highest
– Softer abrasives with smaller particle size, such as concentrate and ore,
produced lower wear rates
• Glass fibre reinforced vinyl ester has higher erosion wear rate than the
tested rubbers and thermoplastics
• The erosion process started with the local removal of the matrix
material and continued with the fibre fragmentation and debonding
from the matrix.

13. The work has been done within FIMECC
LIGHT program funded by Tekes and industry

14. www.tut.fi/rocktrib

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