[en] The carburization and oxidation behavior of HT alloys is investigated theoretically using thermodynamic methods. The calculation of the free reaction enthalpies for the carbides and oxides of the alloy elements in various helium test atmospheres shows that qualitative differences in the corrosion of the test materials are determined by the alloy composition. The composition of the helium test atmospheres, on the other hand, is of secondary importance. In the temperature range 750 - 1000°C, the alloy elements Al, Ti, Si, Nb, Cr and Mn are oxidized. The formation of carbides is possible with the elements Ti, Nb, Cr, Al, Si, W, Mo, Fe, Co and Ni.

[en] Automatic translation: PANAMETRICS humidity sensors are suitable for measuring small H₂O partial pressures in the range of 1 μbar. Thermostatting the sensor's measuring chamber is recommended. The manufacturer's calibration should be checked with an in-situ calibration. The long-term stability of the sensors is unsatisfactory, so checking the calibration values​​after longer use is very important. The method of helium humidification using a freezer and an ice container has proven to be effective. It is also suitable for calibrating the humidity sensors.

[en] Automatic translation: The results of the creep tests with a test atmosphere of heavily contaminated helium are presented in the form of creep and time-strain diagrams. The test materials are NIMONIC alloy 80 A, ALLOY 713 LC, TZM melted, TZM sintered, INCONEL alloy 625, ALLOY IN-586 and HASTELLOY alloy S. Temperature range 650 - 950°C. Service life: 100 - 10,000 h. An influence on the service life by the test atmosphere (HTR helium or air) is not evident. The clear differences in the intensity of the corrosive attack for the various alloy types, however, suggest that the influence of the test atmosphere is effective in long-term operation.

[en] Automatic translation: The CO and H₂ production in the test helium of the creep furnaces can be traced back to the chemical reaction ²C + H₂O --> CO + H₂. The elemental carbon is created by thermal decomposition of methane. The water vapor is either added or is created by degassing the metallic sample tubes near the water-cooled flanges. The depletion of water vapor in the test helium occurs so quickly that from 500°C it is hardly possible to keep a certain water vapor partial pressure in the test helium constant when carbon is deposited on the recipient walls.

[en] Automatic translation: For the investigation of the mechanical behaviour of metall. materials under long-term creep loading, the IRW has 20 single specimen furnaces at its disposal. The load as a significant influencing factor during the test should generate a largely uniaxial stress state in the specimen. The current design of the testing machine often leads to high bending stress components, which depend on the size and direction of the specimen installation. In order to be able to influence the undesirable stresses, the rigid tie rod holder with shoulder head was redesigned as an articulated bearing. Furthermore, a digital displacement recording system was installed with a tap on the load lever of the machine in order to be able to track the creep of the specimen on the lever movement.

[en] Automatic translation: This study deals with the sample strain measurement on the test benches of the ZEMAK I creep test facility. After a general description of the strain measurement, disturbances of a mechanical and test-related nature are analyzed according to their origin and size. The modifications to the tie rod holder and their effects are described. Finally, the technical modifications to the tie rod holder and the alternative to the strain tap on the sample, the load lever tap, are put into practice with the result of a significantly improved measured value curve when tapping the sample and a not entirely satisfactory strain measurement on the load lever.

[en] Automatic translation: Gas chromatographic partial pressure measurements were carried out to investigate the corrosion properties of carbon monoxide in helium. The helium flowed through a metallic furnace recipient with various built-in parts. The tests at 550 - 1000 C with 5 helium impurity states, two flow rates and different metal surfaces in the recipient showed that the partial pressure of the carbon monoxide is essentially reduced by surface reactions. A thin layer of soot formed on the chrome-plated components.

[en] Automatic translation: The carburisation of high-temperature alloys is investigated by gas chromatographic measurements, metallography, carbon analyses and sample weight determinations. The test atmospheres are helium + 100 vpm CH₄ or 100 vpm CO. The samples made of the test materials INCONEL 617, HASTELLOY S and TZM are placed in quartz tubes at a temperature of 950°c. The Mo-based alloy TZM is not corroded, the Ni-based alloys INCONEL 617 and HASTELLOY S are very strongly carburised in the methane-containing test helium. The test helium contaminated with CO causes only slight carburisation and weak oxidation of the sample surface in the Ni-based alloys.

[en] Automatic translation: This report contains the results of a parameter study on the composition of the test helium in ZEMAK II. The partial pressure changes of the helium impurities are measured by gas chromatography. Particularly problematic is the thermal decomposition of the methane during the flow through the sample chambers at temperatures above 950°C. In order to carry out material tests under flowing test helium, it is necessary to it is necessary to select a sufficiently large volume flow rate. The process engineering of the helium circuit in ZEMAK II allows each test stand to be supplied with approx. 100 litres per hour, so that the required tolerances of the PNP test helium up to T = 950°C.

[en] The purpose of this report is to consider the thermodynamic aspects of the behaviour of materials in typical high temperature reactor environments. An earlier report described the use of thermodynamics in predicting the behaviour of materials in impure helium of the type likely to be encountered in HTRs and this report is an extension of the earlier one. A computer programme has been written to facilitate the prediction of materials' behaviour and a detailed description of this programme is given here. The use of the programme is illustrated by evaluating the likely behaviour of given alloy (INCOLOY alloy 807) in a specific helium environment (ZEMAK-I).