Oerlikon (Liechtenstein)

This study examines the implementation challenges of closed-loop supply chains in electronic waste recycling industries through comprehensive case analysis and empirical research. The theoretical framework integrates circular economy principles with stakeholder behavioral dynamics to identify critical bottlenecks in collection networks, reverse logistics, processing technologies, and value chain integration. Examining case studies from specific e-waste recycling businesses shows that successful implementations need to simultaneously resolve technological, organisational, and institutional obstacles. This research illustrates non-linear patterns between the recycling performance and policies’ strictness, highlighting both threshold and tipping points that catalyse sector-wide shifts. A joint government-business model is centred on governance minimalism, multi-tier incentive frameworks, and PPPs focused on infrastructure. It was found that in achieving sustainable closed-loop systems, balancing short-term gains with long-term value through concerted system design, policy architecture, and tech advancement is essential. This provided both the theoretical framework and the practical policy recommendations for the electronics sector’s industrial players that aim to expedite the circular economy shift.

Bu makale, 20. yüzyılın ortalarında Arnavutluk ve Yugoslavya’da komünizm, kült liderliği ve görsel medya arasındaki ilişkiyi incelemektedir. II. Dünya Savaşı’nın ve Balkan bölgesinin kendine has jeopolitik dinamiklerinin ortasında, komünist hareketler ortaya çıkmış ve Yugoslavya’da Josip Broz Tito ile Arnavutluk'ta Enver Hoca tarafından yönetilmiştir. Bu liderler, fotoğraflar ve posterler gibi çeşitli görsel medya araçlarıyla liderliklerini mit haline getirerek güçlü direniş yapıları kurmuşlardır. Bölgenin coğrafi yapısı ve Batı’nın doğrudan müdahalesinin olmaması, Balkanlar’daki komünist bloğun gelişmesini ve Moskova etrafında iyi örgütlenmesini sağlamıştır. Tito’nun Yugoslavya liderliği ve Hoca’nın Arnavutluk’taki yükselişine verdiği destekle beraber bölgedeki komünist direniş sağlamlaşmıştır. Savaştan sonra, her iki lider de Stalinist söylemleri rejimlerine entegre ederek Sovyetler Birliği ile bağlarını güçlendirmiştir. Roland Barthes’ın göstergebilimsel yöntemleri kullanılarak analiz edilen kişilik kültleri, komünizmi meşrulaştırmada ve ideolojik bağlılığı güçlendirmede önemli bir rol oynamıştır. Tito’nun 1948’de Stalin’den kopması, özerklik ve Titoizm ideolojisine doğru bir yönelimi işaret ederken, Hoca Stalinist ilkelere sıkı sıkıya bağlı kalmıştır. Bu makale, bölgedeki komünist liderliğin şekillenmesinde yerel ve uluslararası faktörlerin karmaşık etkileşimini vurgulamakta ve siyasi söylem ile kişilik kültlerinin inşasında görsel medyanın kalıcı mirasının altını çizmektedir.

Architectural designs involving Al- and/or Si-containing top coatings present an effective approach to protect oxidation-sensitive materials such as binary transition metal (TM) diborides against high-temperature oxidation. Using reactive arc evaporation, Al-Si-N, Al-Si-O, and Si-O top coatings were applied on sputter-deposited WB1.9, TiB2.7, and HfB2.4 thin films, respectively. A pure Si adhesion layer was introduced prior to the deposition of both oxide-based top coatings (Al-Si-O & Si-O) to prevent in-situ oxidation of the diboride base layers. During thermal annealing up to 1200 °C, Al-Si-O and Si-O provided outstanding oxidation resistance on top of TiB2.7 and HfB2.4, while limited adhesion was observed on WB1.9 at elevated temperatures. Contrary, Al-Si-N protected architectures suffered from accelerated oxidation beyond 800 to 1000 °C. Isothermal annealing in ambient air at 1200 °C for 30 h confirmed the long-term stability of the oxide-based top coatings, revealing no decohesion or oxygen inward diffusion beyond the Si interlayer. Complementary TEM analysis showed that the Si-O top coating forms a dense SiO2 scale above the columnar HfB2.4, while the formation of a mullite scale (3Al2O3·2SiO2) and pronounced recrystallization is recorded for the Al-Si-O protected HfB2.4. In summary, the Al-Si-O- and Si-O-based top coatings demonstrated exceptional high-temperature oxidation resistance, fully protecting the TM-diborides from oxidative attack.

Superlattice structures enable the simultaneous enhancement in hardness (H) and fracture toughness (KIC) of ceramic-like coatings. While a deeper understanding of this effect has been gained for fcc-structured transition metal nitrides (TMN), hardly any knowledge is available for hexagonal diborides (TMB2). Here we show that superlattices can—similarly to nitrides—increase the hardness and toughness of diboride films. For this purpose, we deposited TiB2/WB2 and TiB2/ZrB2 superlattices with different bilayer periods (Λ) by non-reactive sputtering. Nanoindentation and in-situ microcantilever bending tests yield a distinct H peak for the TiB2/WB2 system (45.5 ± 1.3 GPa for Λ = 6 nm) but no increase in KIC related to a difference in shear moduli (112 GPa). Contrary, the TiB2/ZrB2 system shows no peak in H, but for KIC with 3.70 ± 0.26 MPa∙m1/2 at Λ = 4 nm originating from differences in lattice spacing (0.14 Å), hence causing coherent stresses retarding crack growth.

Structural imperfections such as nano-columnar tissue phases constitute a morphological design feature in protective thin films. Especially in the rising group of PVD transition metal diborides, excess Boron is known to form nm-sized B-rich precipitations in-between nano-crystalline domains. Here, we focus on super-stoichiometric TiB2 + z thin films, varying the stoichiometry from TiB2.04 to TiB4.42 (B: 67–82 at.%). The tissue phase fraction and thickness is mainly governed by the B content and corresponding deposition conditions. A decreasing tissue phase width from ≈ 3–1 nm leads to an increasing critical stress intensity factor KIC of ≈ 40%.

The impact of configurational entropy, enthalpy, and strain energy on the phase stability of high-entropy materials has not yet been investigated quantitatively. We used ab-initio calculations to predict the driving force for decomposition of 126 equimolar Al-containing high-entropy sublattice nitrides (HESN), which are all metastable with respect to all corresponding equimolar lower-entropy nitride phases. The entropy stabilization of ≈−0.06 eV/at. at 1073 K is overruled by the 0.10-0.27 eV/at. enthalpy-governed driving force for decomposition. Stabilization is however predicted for 22 compositions due to the −0.01 to - 0.28 eV/at. strain energy contribution caused by large differences in equilibrium volume between the HESN and their decomposition products. The predicted stabilities are consistent with diffraction and tomography data of annealed nitride coatings. Hence, it is evident that only strain enables the stabilization of the here studied Al-containing HESN, while the entropic contribution is overruled by endothermic mixing.

Reactively magnetron sputtered high-entropy metal-sublattice (Al,Cr,Nb,Ta,Ti)N coatings have been alloyed with Si concentrations between xSi = 6.4 and 15.0 at.%. All coatings are single-phase fcc structured and their hardness initially increases from ~32 to 35 GPa with Si-alloying up to xSi = 9.8 at.%, and then decreases to ~24 GPa for higher Si contents. Contrary, the indentation modulus E continuously decreases from ~470 to 350 GPa by Si-alloying. Also, the decomposition of the fcc structure during vacuum annealing is shifted from 1000 to 1200 °C with the addition of Si. The hardness initially increases during vacuum annealing and reaches a maximum of 37 GPa with Ta = 1000 °C at xSi = 12.0 at.%. During oxidation experiments in ambient air at 850 °C for up to 100 h, a 2700 nm single-phase rutile-structured oxide scale forms at the Si-free (Al,Cr,Nb,Ta,Ti)N with a parabolic growth rate. The rate changes to a logarithmic-like behavior with the addition of Si, resulting in only ~280 nm oxide scale after 100 h. Also, for the Si-containing coatings, the oxide scale shows only one crystalline rutile structure. The pore size in the oxide scale of the Si-free coating is considerably reduced by Si-addition. The oxides growing at the Si-containing coatings show an opposing Si- and Cr-gradient - with much smaller pores in the Si-rich inner region - which shows a gradual transition to the remaining nitride. Ab initio based calculations confirm that the formation of a single-phase rutile-structured solid solution oxide, (Al,Cr,Nb,Ta,Ti)O2, is energetically preferred over separate phases above 509 K, due to the higher configurational entropy. Below this temperature the decomposition towards (Al,Ta,Ti)O2 + (Cr,Nb)O2 would be favored (when considering just chemical contributions), but kinetically restricted.