No abstract

No abstract

No abstract

No abstract

Vacuum brazing now has been established as a proven and versatile joining technique in numerous application areas. Besides high joint quality design engineers can take advantage of a broad range of different material combinations. Using vacuum brazing he is able to realize new functions or to improve existing product performance and/or cost situation.Obviously a service contractor is engaged in all industrial application areas and has to handle all engineering materials. In-depth knowledge and a well educated and trained staff is essential to fulfil customer needs. Further success factors are state-of-the-art equipment, a proven quality management system and an international network with research institutions.Equipment: In principle vacuum brazing can be done in the same furnaces which are used for vacuum hardening. But for more sophisticated tasks a high vacuum pump unit and sometimes a furnace with an all metal hot-zone is required. To handle a broad range of applications heating with gas convection or partial pressure with nitrogen and argon and a controlled gas quenching with gas pressures above 6 bar should be possible (Fig. 1).Materials: Actually service contractors are faced with a broad range of materials because a well selected and treated material is responsible for later functionality, performance, service time and costs of components or even entire processes. Besides steels, super alloys, titanium and titanium alloys, engineering ceramics and even superhard materials as diamond and cubic boron-nitride (cBN) are frequently used. Composites and intermetallics gain increasing importance and define new demands on equipment and process management.Selection of brazing alloys has to consider above mentioned criteria. Additionally specific properties of base materials as chemical compatibility with the braze alloy (wetting, diffusion), hardening temperature, melting point, evaporation pressure and reaction with process media have to be taken into account.Quality management: Performance of components is improving constantly to enable producer's competitiveness on global markets. For this reason design engineers employ materials which offer a maximum performance to cost ratio. Joining and heat treatment processes have to maintain and even to improve materials properties. Very often process parameters can varied in a small range only because small deviations already can have a tremendous negative impact on component behaviour.These technical reasons but also aspects resulting from product liability prerequisites an integrated quality management system. All processes have to be documented with clearly and understandable traceability. Qualification of employees and process stability of equipment have to be on high level and improved steadily.Certification according to ISO 9000 is standard for ambitious service contractors. To serve customers in automotive and aircraft industry more demanding quality systems are required.State-of-the-art: Paper Recycling: The need to save resources and a growing environmental aware...