Views
5 years ago

2 µm - eTheses Repository - University of Birmingham

2 µm - eTheses Repository - University of Birmingham

of 0.05

of 0.05 to 0.25 MPa to determine the influence of differential pressure ΔP on permeability. The optimized pressure of 0.1 MPa, which was a compromise between measuring time and preform fracturing, was then used for further measurements and the temperature of the fluid was recorded. A schematic of the apparatus used is shown in Figure 3.7 b). a) b) Green part pressing direction perpendicular 77 ΔP Δp (air) water T H2 0 Preform V water seal aluminium ring hot-melt glue jont Figure 3.7 Schematic: a) pressing direction and location of the samples used for permeability measurements. b) apparatus for preform permeability measurements, exemplarily when using water as a fluid. The mass of water was weighed continuously with a Mettler-Toledo PG-5002 SA balance with a resolution of 10 mg. The flow rate vl of water was calculated by using the density of the fluid at test temperature. The data for density and viscosity η of the fluids were taken from tables (160) . The specific permeability KS of the preform was calculated as: K η L vl A ∆P S = Equation 43 where L was the thickness of the preform in the direction of the fluid flow, A the projected area and ΔP the gas pressure applied to the fluid. 3.3.8. Compressibility The compressibility of the preforms was characterised using two different methods. The first was a compression test on rectangular samples loaded uniaxially between two parallel plates. The second was an isostatic compression test.

The compressive strength, σc , of the preforms was determined on an Instron 1362 universal testing machine at the University of Karlsruhe using samples of dimensions 16 mm x 16 mm x 8 mm according to European Standard ENV 658-2 (161) . Six samples of each type of preform were tested. a) b) a) b) ΔV P mercury preform flexible canning mould Pressure p /MPa Pressure (MPa) 250 200 150 100 50 0 0 20 40 60 80 78 Time (s) t /s Figure 3.8 a) Schematic of the set-up used for isostatic compression tests on preforms performed on a mercury porosimeter. b) Time-pressure schedule The isostatic compression tests were conducted on a mercury intrusion porosimeter as described in 3.3.6. The preform samples which measured 6 mm x 4 mm x 3 mm were cut out of the preforms and ground to produce smooth surfaces and round edges. Each sample was canned in a latex finger from a latex glove which was evacuated down to 0.01 mbar and hermetically sealed by applying a knot to its open end. The sample was set into the cavity of a porosimeter as shown schematically in Figure 3.8 a). Compared to the pore size measurements, a relatively fast incremental pressurization programme was applied, leading to circumstances as close as possible to preform infiltration. The pressurization curve is given in Figure 3.8 b). The volumetric change, ΔV, at each pressure point was recorded. The volume changes at pressures below 0.1 MPa were neglected, since it was assumed that these represented intrusion and compression of the latex and not

PDF File 2 - University of Alabama at Birmingham
no· l'2-'1t1 - Repository - Texas A&M University
eTheses Repository - University of Birmingham
chapter 1 - eTheses Repository - University of Birmingham
MODULE 2 - eTheses Repository - University of Birmingham
eTheses Repository - University of Birmingham
eA - eTheses Repository - University of Birmingham
eTheses Repository - University of Birmingham
B - eTheses Repository - University of Birmingham
Cymbeline - eTheses Repository - University of Birmingham
1 - eTheses Repository - University of Birmingham
Caroline Winstanley - eTheses Repository - University of Birmingham
epinician precepts - eTheses Repository - University of Birmingham
Witch Shoes - eTheses Repository - University of Birmingham
pains of sin - eTheses Repository - University of Birmingham
5% - eTheses Repository - University of Birmingham
here - eTheses Repository - University of Birmingham
View - eTheses Repository - University of Birmingham
J - eTheses Repository - University of Birmingham
B - eTheses Repository - University of Birmingham
Table of Contents - eTheses Repository - University of Birmingham
chapter 1 - eTheses Repository - University of Birmingham
THE GOD–MAN - eTheses Repository - University of Birmingham
Engineering texts - eTheses Repository - University of Birmingham
Life on Wings - eTheses Repository - University of Birmingham
ford madox brown - eTheses Repository - University of Birmingham
Rewriting history - eTheses Repository - University of Birmingham
Four Quartets - eTheses Repository - University of Birmingham
part i - eTheses Repository - University of Birmingham
PIERRE BOAISTUAU - eTheses Repository - University of Birmingham