100 Jahre HV‐Pumpe von Wolfgang Gaede. 100th Anniversary of Gaede's High Vacuum Pump

In 1905 Wolfgang Gaede invented a sturdy, quickly operating high vacuum pump, which was easy to use. It was produced and distributed under licence from E. LEYBOLD’s Nachf. This firstly allowed the application of high vacuum technique to industriel production. Gaede continued to work with Leybold just to the end of his life in 1945.     

Renaissance einer Hundertjährigen. Die Molekularpumpe von Wolfgang Gaede

New Success after 100 years: the ?Molecular Pump”? of Gaede The molecular drag pump was invented by W. Gaede in 1908. The design of the prototyp needed two years, and another two years later the first molecular pumps were 1912 ready for selling. But the sophisticated design and handling and the war 1914 limited the world wide application of the pump. Now at the end of the 20^th century the invention was successfully used as final compression stage in turbomolecular pumps.     

Gaedes rotierende Quecksilberluftpumpe

The rotary mercury pump of Gaede Wolfgang Gaedes invention of a quickly acting high vacuum pump was induced by his studies about the Volta effect. The so far known pumps were not able to create sufficient low pressure to optain very clean surfaces. Alfred Schmidt, owner of the E. Leybold’s Nachfolger Company, Cologne, learned from the publication about the demonstration of the pump its importance. He made an agreement with Gaede to develop together the invention during 1906 and 1908 to a product for use in industrial application – first step into industrial high vacuum technology     

Wolfgang Gaede ‐ Wegbereiter der Vakuumtechnik

The inventions of Wolfgang Gaede were the beginning of the extensive industrial application of vacuum technology: the 1905 invented high vacuum mercury pump simplified the production of electric bulbs. From this time Gaede joined the company E. Leybold's Nachfolger research & development activities for 40years. Three of his inventions, the diffusion pump, the (turbo‐) molecular pump and the principle of “gas ballast” are worldwide in use even today. The most important stations of Gaede's biography are reported.     

Der Beginn einer Erfolgsgeschichte

The beginnings of a successful story The exciting invention of the molecular Pump by Wolfgang Gaede was followed by his new ‘Device of Producing High Vacua’ in 1913. It was announced in the second edition 1913 of E.Leybold's cataloge. Three years later Langmuir in the USA presented a similar pump called ‘condensationpump’, but with clearly better pumping speed. Another design of a pump with two stages was invented by Prof. Volmer in Berlin. Other European companies announced similar pumps. Because Gaede claimed the prinziple of evacuating gas by diffusion, he and Leybold succeeded in making all of them to ask for licences. Respective to Langmuir they exchanged licence to each other. By the time this ‘diffusion pump’ was produced from metal instead of glas, and used special mineral oil, not mercury. In the middle of the 20.century it became a most important tool for creating high vacuum, available with a few liters per second to some thousend liters of pumping speed.     

Geschichte der Vakuumtechnik. History of Vacuum Technology

The history of vacuum technology is more than 2000 years old. Over the past 400 years scientists, engineers and inventors such as Torricelli, Pascal, von Guericke and Gaede have been engaged in vacuum technology. Vacuum has become an essential instrument in science and technology and many processes could not exist without it. Furthermore vacuum technology has been developed as an individual industrially applied technology. The article describes the development of vacuum technology from ancient philosophical speculations about the mercurial glass pipe to the modern diffusion pump.     

Der Gasballast

Wolfgang Gaedes last important invention: the Gasballast Gaedes invention of the rotating Mercury‐vacuumpump made highvacuum technology available for the industrial production. A second and third impact was given by gaedes molecular‐ and diffusionpump respectively, both depending on physikal effects firstly used for vacuum generation. Vacuum technology becomes increasing importance but the common oil sealed rotating pumps for fine vacuum suffer from contamination of the oil by vapor condensation. It was another invention from Gaede that eliminated this handycap in a very elegant way: the gasballast that is up to now a very important feature of this type of pumps.     

Anwendung von Methoden der Bruchmechanik zur Lebensdauerverbesserung von Umformwerkzeugen

Application of Fracture Mechanics for the Improvement of the Life Time of Forming Dies An investigation was undertaken to determine the life times of dies when these life times are determined by crack propagation from such stress raisers as notches. Notched DCB specimens were used to investigate the processes of crack initiation and propagation in the high temperature steel X 40 CrMo V 51 at 500°C. The results showed that the life times depend both on the heat treatment of the material and also on the length of hold time at temperature. Hold times during the forming process should be minimized in order to avoid fast creep crack propagation.     

Komplexe Bewertung von Indentereindrücken zur Charakterisierung von Konstruktionskeramik

The induction of indentations in brittle materials and their evaluation result in information useful for the characterization of materials. In addition to the fracture-mechanical evaluation of the indentations, i.e. of the incipient cracks resulting from them, which cracks are used for determining the fracture toughness. Information regarding the hardness, critical size of surface defects, characteristic quantities of crack propagation, durability as well as existing internal stresses can be derived.     

Das Zeitstandverhalten von Feinblei

The creep behaviour of sheet lead . The exact dimensioning of building components subject to deformation through creep is becoming an increasingly important factor in modern engineering. A search of the literature for the mechanical properties of sheet lead shows that differing statements are made on the mechanical behaviour of lead (1–3). Above all, it is repeatedly found that the strength properties over long periods are derived from short-term trials and that characteristic values such a expansion rate and creep rate are given, which have been determined from such trails. In order that definite information can be given on the strength properties of lead and its alloys used for technical purposes, genuine creep trails over long periods are necessary.     

Die Kaltverfestigung von Nickelbasislegierungen

Strain Hardening of Nickel Base Alloys Tensile-, impact-, and hardness test were performed on solution treated and cold worked Nimonic 86 and Inconel 625. The characteristic values of strain hardening from the tensile-, impact-, and hardness tests were correlated, namely the strain hardening exponent m as determined from the stress-strain-curve of the tensile test. The impact test gave the lateral expansion and the hardness test the value (n?2), which corresponds approximately to the strain hardening coefficient of the tensile test.     

Herstellungsverfahren von Metall-Keramik Schichtverbundproben

Manufactoring process for metal-ceramic adhesive joint specimens . A technique is described how to manufacture adhesive joints made from ceramic and metal-state bonding without formation of an intermediate layer. The prior condition for adhesion is a well formation matching of the bonding surfaces during the whole welding procedure. Plastic flow of the metal or ceramic pert leads to a maximum matching og the contacting surfaces. Bending and shearing of the joint during the welding process must be suppressed. The inductive heating is appropriate to from an unifrom temperature distribution and a homogeneous plastic zone to give a symmetrical matchimg. The bond strength is characterized by fracture mechanics methods.     

Kostenstruktur von Plasmaverfahren

Cost Structure of Plasma Processes — The share of investment costs and operating expense in vacuum coating processes At a first glance coating costs of plasma processes seem to be dominated by high investments. Here it is shown that operating costs are at least of the same importance. Thus, it is reasonable to accept coating costs as only one contribution amongst others to the overall production costs. The example ?solar cells”? shows that further enhancement of the coating process is less effective compared to an increase of energy conversion efficiency. On the other hand it appears more effective for cost reduction of hard coatings to decrease energy consumption and to increase the deposition rate instead of minimization of investment costs for the coating machine. The cost structures of depositions from the liquid phase and plasma processes are of the same order but growing environmental demands clearly favor the latter one (no liquid waste, etc.). The commonly used argument, that it is always preferable to run coating processes at atmospheric pressure without the use of (expensive) vacuum equipment rather than under vacuum conditions needs to be reconsidered particularly when noble gases are necessary at atmospheric pressure to obtain equal qualities of the coatings.     

Gasdruckschwingungsverteilung im Arbeitskanal von Seitenkanalverdichtern

The magnitude of energy transfer in side channel compressors depends on intenseness of gas pressure oscillation and transport of specific momentum in the side channel. For analysis of energy transfer from impeller to gas, the static pressure distribution and the intenseness of gas pressure oscillation in meridian profile of the side channel subject to radius and also to axial distance to impellers grid was measured with a high tightness of reading points. In order to plot the intenseness of gas pressure oscillation in meridian profile of the side channel, gas pressure oscillation in side channel has been characterized by RMS, peak value and amplitude value of gas pressure oscillation at blade rotation frequency. The results of gas pressure oscillation and tangential velocity progression in side channel from laser measurement show that the strongest gas pressure oscillations and highest velocities appear in outer region of the impeller and side channel, which refer to intense energy transfer in this region.     

Untersuchung von Oberflächenschutzschichten von Gasturbinenlegierungen

Investigations on protective coatings on gasturbine alloys. It has been found by investigations of specimens of a combustion chamber pilot plant and also by experiences with gasturbines that aluminide or chromium aluminide coatings are only slightly protective under working conditions of industrial gasturbines. Chromium coatings have a distinctive better protective efficacy and are surpassed in this quality by silicide coatings. It was possible to give information on the development of silicide phases on Nimonic 105. Under the conditions of corrosive attack a surface layer of Nickelolivine is formed and the silicide phases are changed in direction of ternary phases. Even when chromium sulfides are formed in the silicide layer the specimens are stable under the test conditions. By investigations on an airfoil made from B 1900 with a protective coating of Aluminium and Silicon the presence is shown of a ternary Laves phase with Silicon.     

Hochskalieren von Plasmaprozessen

Plasma processes are usually worked out in a small-scale environment. In order to meet the requirements of industrial applications, they have to be upscaled. A procedure for upscaling is desribed, starting from theoretical and empirical data, applying designed experiments and online diagnostics. PE-CVD of amorphous silicon serves as an example.     

Berechnung des numerischen Einflusses von Zerlegeschrittweite und Auswertegleichung auf die Bestimmungsgenauigkeit von experimentellrechnerischen Eigenspannungsermittlungen

Calculation of the numerical influence of dividing step depth and evaluation equation on the determination accuracy from experimentally – calculated residual stresses . Residual stress determinations are often used for the estimation of mechanical and corrosion behavior of materials. Interesting is, depending on the material property to be estimated, the sign, the distribution or the absolute value of the existing residual stresses. Hence, the question about the accuracy of any residual stress determination in many cases is of great importance. The present investigation relates itself to the influence of errors from experimentally – calculated residual stresses by dividing method. For this generally used determination method will give a possibility for calculating the error resulting from numerical evaluation of investigation results, here shown with the example of a beam. Apart from the well known Stäblein-Equation [2] two finite determination equations, derived during the work, are investigated by varying the depth of dividing step.     

Festigkeit von Werkstoffen bei Aufprallbeanspruchungen

Strength of Materials in Case of Mechanical Impact The resistance of materials to mechanical impact was investigated in the context of safety of guards used in machine tools. Such guards are meant to protect persons from injuries caused by parts which, in the case of technical failure, are projected at high speeds out of the work zone of the machine. Impact tests with blunt, cylindrical projectiles were carried out on steel and aluminium sheets and on polycarbonate and polymethylmetacrylate shields. The measure of impact strength was the ultimate projectile energy which could be applied to the specimen without causing perforation. The impact strength of new 8-mm-polycarbonate shields turned out to be approximately comparable to that of 3-mm-steel sheets St 12.03. Polycarbonate, however, when it is exposed to cooling lubricants as they are used in machining processes, suffers from a strong reduction of its impact strength. In the tests, there was good proportionality between the impact strength of the materials and their thickness, ultimate tensile strength and fracture elongation. In addition, the impact strength increased as the projectile diameter got bigger.     

Maßänderungen von Zinkdruckgußlegierungen infolge von Alterung

Changes in dimension of zinc die-casting alloys due to aging . It is known since a long time that die-cast elements are subject to slight changes in dimension even when they are made of high-grade zinc alloys standardized for that purpose. But in prior research it was apparently still unknown that the amount of these changes is influenced, among other things, by the cooling conditions of the pieces following the casting process. It is therefore impossible to compare off-hand the values coming from different sources. The changes in dimension were reinvestigated for that reason with regard to the cooling conditions, and the results were some new findings in this field.