Abstract:
A sample holder for use in a scientific instrument requiring accurate and precise measurements of temperatures. The sample holder includes a ceramic sample cup diffusion bonded to a ceramic beam or to a ceramic adapter. A thermocouple is welded to the bottom of the sample cup.
Abstract:
A balance for a simultaneous differential thermal analysis instrument that combines gravimetric measurements with measurements that require propagation of electrical signals from the sample holder to an apparatus for recording the electrical signals. In one embodiment of the present invention, conductive cross-flexure pivots are used in a parallel guided balance to mechanically and electrically couple the components of the balance mechanism to the apparatus that records the electrical signals.
Abstract:
Systems and methods for minimizing extraneous forces and calculating corrected weights of samples based on buoyancy factors for a thermogravimetric analyzer (TGA). The TGA includes a balance chamber and a furnace configured to heat a sample. A null balance is provided in the balance chamber and is used to measure the sample weight change during heating. The furnace includes a cylinder open at the top to receive a sample. The bottom of the cylinder is closed except for a small hole that allows a thermocouple to pass through. An infrared heat source may be provided to heat the cylinder. The balance chamber can be thermally isolated from the furnace using an actively cooled plate and a system of heat shields disposed between the furnace and balance chamber. A thermocouple disk is further provided to limit gas flow in the furnace and increase reliability of sample weight measurements.
Abstract:
A method and system for calculating a heat flow to a sample in a differential scanning calorimeter (DSC). The DSC has a sensor within an enclosure comprising an absolute temperature measurement detector for measuring the temperature of a base position on the sensor, a first differential temperature detector for measuring the temperature difference between a sample position and the base position, and a second differential temperature detector for measuring the temperature difference between a reference position and a sample position. Thermal resistances and heat capacities of the DSC are calibrated. The DSC is operated, and the heat flow to the sample is calculated using a method that accounts for the leakage heat flows.
Abstract:
A method and system for calculating a heat flow to a sample in a differential scanning calorimeter (DSC). The DSC has a sensor within an enclosure comprising an absolute temperature measurement detector for measuring the temperature of a base position on the sensor, a first differential temperature detector for measuring the temperature difference between a sample position and the base position, and a second differential temperature detector for measuring the temperature difference between a reference position and a sample position. Thermal resistances and heat capacities of the DSC are calibrated. The DSC is operated, and the heat flow to the sample is calculated using a method that accounts for the leakage heat flows.
Abstract:
A sensor for a heat flux differential scanning calorimeter in which the differential temperatures are measured between locations external to the regions of heat exchange between the sensor and sample containers. The measured differential temperatures respond to the magnitude of the heat flow rate between the sensor and the sample and reference containers and are rendered insensitive to variations in the magnitude and distribution of thermal contact resistance between the sensor and the containers.
Abstract:
A sensor for a heat flux differential scanning calorimeter in which one absolute temperature measurement and two differential temperature measurements are used. The sensor is calibrated and used based on a four-term model heat flow equation. The calibration is carried out in two experiments which are used to calculate the sensor thermal resistance for the sample and reference positions, respectively, and the sensor heat capacity for the sample and reference positions, respectively. Differential scanning calorimeters using this sensor exhibit improved resolution, improved baseline performance and improved dynamic response.
Abstract:
A power compensation differential scanning calorimeter that uses one absolute temperature measurement, two differential temperature measurements, a differential power measurement, and a five-term heat flow equation to measure the sample heat flow. The calorimeter is calibrated by running two sequential calibration experiments. In a preferred embodiment, the first calibration experiment uses empty sample and reference pans, and the second calibration experiment uses sapphire specimens in the sample and reference holders. In an alternate embodiment, sapphire calibration specimens are used in both the first and second calibration experiments.
Abstract:
A heat shield and insulation system comprised of multiple layers of metallic sheets separated by small protrusions or dimples in the metallic sheets. The multiple layers are formed by spirally winding a coil of the metallic sheet around the sample enclosure. The protrusions are formed by stamping the metallic sheets, preferably in a random patterns, such that one set of protrusions does not nest in the protrusions formed in a neighboring sheet. The spacing between the layers of metallic sheets is small, such that convection does not occur in the space between the layers. Accordingly, the heat transfer between the layers of the metallic sheets is primarily radiative or via thermal conduction through the gas. The two ends of the helically wound metallic sheet are insulated by multiple thin metallic disks.
Abstract:
The present invention is an infrared-heated differential thermal analyzing instrument. The instrument uses an actively cooled heat sink, and a heat flow restricting element connecting the heat sink to a differential thermal analysis sensor. An IR heater directs IR radiation onto the lateral surfaces of the heat sink and the heat flow restricting element. These lateral surfaces are polished and coated with a high IR reflectance coating, so that heat absorption is minimized. The IR heater preferably uses either elliptical or parabolic mirrors to focus the IR radiation onto the heat sink and the heat flow restricting element. A second embodiment of the invention uses two heat sinks, and two heat flow restricting elements, with one heat sink and one heat flow restricting element mounted on either side of the differential analysis thermal sensor.