We just finished a very successful 3 day long heating and rig stiffness test. The results were very consistent and show a loading stiffness of ~15 µm / kN at a range of temperatures (300˚C to 700˚C) at 0.6 GPa confining pressure. Since we currently operate only with one pressure vessel, we stay in the lower limits of the P-T space we can achieve to prevent pressure vessel failure and delays to our tests. Our main aim is to reach about 2 GPa confining pressure and 1150˚C – this will allow us to deform partially molten mantle rocks with a simple NaCl pressure medium.
Sample assembly after experiment – note the large grain size of the salt between the furnace (black) and sample (white Al2O3 piston in the center). Grain growth occurs over long time periods at high temperatures.Results from the stiffness tests – note the inflection point at about 5 mm displacement, this corresponds to the hitting of the sample with the WC piston. The subsequent loading slope and unloading slope are used to asses the rig stiffness.Furnace performance – Volts and Amps as a function of sample temperature. Initial peaks and oscillations are due to the search for right PID parameters in the Eurotherm controller. Shut off at ≈ 700˚C was used to estimate the maximal quenching rate – control was recovered at ≈400˚C. The maximum power our heating system can deliver is 500 A and 10 V which is enough to probably melt even the pressure vessel…
