A new copper based hermetic sealing material: A comparison with AgCu28GeCo0.3
For vacuum brazing applications Hermetic Sealing Materials (HSM) with low partial pressure are widely used to join copper or stainless steel parts. For joining copper AgCu28 is a widespread material, which is well characterized and investigated. For stainless steel, AgCu28Ge2Co0.3 is commonly used if the same brazing temperature as AgCu28 is required. Umicore Technical Materials has developed a new copper-based HSM. The tensile strength of the stainless steel joints on stainless steel is comparable to AgCu28Ge2Co0.3 and the wettability is significantly improved. In this article, the physical properties of the alloy and its brazed joints will be presented in comparison to AgCu28GeCo0.3. However, today the silver content of HSMs is more in focus than in the past decades, because it has the biggest impact on the material prices. To accommodate this trend the total silver content of the new HSM is reduced by almost 44 %.
Measurement of contact angle and work of adhesion at high temperature
A critical review is given of the present state of knowledge and future perspectives in high-temperature contact angle measurement. Experimental results obtained by the different versions of the sessile drop method and by various procedures are given in order to illustrate the two main sources of scatter in wettability data, the first being related to the quality of the substrates and the second to control of the furnace atmosphere.
Scaffolds Containing Spirulina sp. LEB 18 Biomass: Development, Characterization and Evaluation of In Vitro Biodegradation.
Polymer nanofibers are nanomaterials that can be used as scaffolds in tissue engineering. The objective of this study was to develop, characterize and evaluate the in vitro degradation of a biomaterial consisting of nanofibers produced from biodegradable and biocompatible polymers with potential applications as a scaffold for tissue regeneration and containing Spirulina sp. LEB 18 biomass as the bioactive compound. The polymers used were poly(hydroxybutyrate-co-hydroxyvalerate) and polycaprolactone. The polymeric solutions exhibited sufficiently high viscosity to produce uniform nanofibers with diameters between 335 and 617 nm. The applied conditions were as follows: a voltage of 25 kV, a distance from the capillary to the collector of 120 mm, a capillary diameter of 0.80 mm, and 12% polycaprolactone and a blend of 5% polycaprolactone and 10% poly(hydroxybutyrate-co-hydroxyvalerate). The biomass was incorporated into the nanofibers at a concentration of 3%, and the incorporation was confirmed using confocal microscopy. The nanofibers were characterized using differential scanning calorimetry and thermogravimetric analysis, which showed that the addition of biomass did not alter the thermal properties of the biomaterial. The addition of biomass improved the tensile strength and elongation of the scaffolds compared with those produced with polymers alone. A biodegradation assay showed enzymatic action toward the biomaterial, simulating the behavior of natural tissue. Based on the analysis, it was concluded that the scaffolds that were produced have the potential to be applied in the field of tissue regeneration as biomaterials with pharmacological properties.