Conventional Production Routes Research Articles

Process Parameter Optimisation in Laser Powder Bed Fusion of Duplex Stainless Steel 2205

Additive Manufacturing (AM) appears as a very interesting alternative to conventional production routes for alloys and metals, thanks to the fact that at the end of printing, the final product is obtained directly. The present article looks for the inclusion of duplex stainless steel 2205 (DSS-2205) in the commercial catalog of steels utilized in powder bed fusion (PBF) technologies, specifically applying the selective laser melting (SLM) technique. The main objective is to establish optimal printing parameters that reproduce the closest results to the base material properties. To achieve this, the response surface method was used in the methodology and experimental design, studying the parameters of laser power, scanning speed, and hatching distance. A reference material, machined from a hot-rolled plate, was utilized to compare the results obtained through tensile strength. Lastly, the optimal parameters have been obtained for this stainless steel. Additionally, a study of heat treatments has been developed, aiming to optimize the austenitization process, achieving an improvement in mechanical properties. A steel with mechanical properties practically identical to those of steel produced using conventional techniques has been obtained through SLM.

Combined Effect of Particle Reinforcement and T6 Heat Treatment on the Compressive Deformation Behavior of an A357 Aluminum Alloy at Room Temperature and at 350 °C

Solid state sintering of cast aluminum powders by resistance heating sintering (RHS), also known as spark plasma sintering or field-assisted sintering technique, creates a very fine microstructure in the bulk material. This leads to high performance material properties with an improved strength and ductility compared to conventional production routes of the same alloys. In this study, the mechanical behavior of an RHS-sintered age-hardenable A357 (AlSi7Mg0.6) cast alloy and a SiCp/A357 aluminum matrix composite (AMC) was investigated. Aiming for high strength and good wear behavior in tribological applications, the AMC was reinforced with a high particle content (35 vol.%) of a coarse particle fraction (d50 = 21 µm). Afterwards, separated and combined effects of particle reinforcement and heat treatment were studied under compressive load both at room temperature and at 350 °C. At room temperature compression, the strengthening effect of precipitation hardening was about twice as high as that for the particle reinforcement, despite the high particle content. At elevated temperatures, the compressive deformation behavior was characterized by simultaneously occurring temperature-activated recovery, recrystallisation and precipitation processes. The occurrence and interaction of these processes was significantly affected by the initial material condition. Moreover, a rearrangement of the SiC reinforcement particles was detected after hot deformation. This rearrangement lead to a homogenized dispersion of the reinforcement phase without considerable particle fragmentation, which offers the potential for secondary thermo-mechanical processing of highly reinforced AMCs.

Surface Integrity of 20MnCr5 Laser Powder Bed Fusion parts subject to contact fatigue test

Additive Manufacturing (AM) is vital for industrial innovation, offering high potential for groundbreaking solutions. However, its successful implementation still depends on overcoming several challenges. Particularly, the assessment of surface integrity in AM-generated components, and its degradation when subjected to contact stresses presents an ongoing endeavor. Within this context, the current work delves into the study of the surface integrity of 20MnCr5 case-hardened samples manufactured through laser powder bed fusion (L-PBF), as well as delves into the investigation of surface failure progression when the samples are subjected to cyclic contact stresses. This study encompasses the analysis of residual stresses, hardness, and roughness of specimens manufactured through both additive and conventional production routes. The study’s findings show that it is feasible to attain analogous surface quality when proper finishing is applied to L-PBF samples. Although, despite the comparable surface quality, the contact fatigue performance was significative lower on the AM sample when compared to the conventionally manufactured. Additionally, additive manufacturing brings up new challenges to performance by presenting a heterogeneous stress distribution and sub-superficial porosity. In conclusion, to attain a desirable surface integrity for additive manufactured parts, further research should not only focus on improving the process parametrization but should also developing finishing routes especially oriented to additive manufacturing, considering therefore how the interaction between the manufacturing processes will evolve into a desirable surface integrity state.

Bio-based production of medium-chain carboxylic acids from food waste and sludge without chemical addition: The pivotal role of mix ratio and pretreatment

Medium-chain carboxylates such as caproic acid, have a plethora of applications, ranging from food additives to bioplastics, and can be produced via microbial chain elongation (CE), a process that can be more sustainable than conventional production routes. During CE short fatty acids accept electrons from donors as lactate or ethanol elongating into medium-chain carboxylates with higher economic value and easier recoverability. Nowadays, waste activated sludge (WAS) and food waste (FW) are the most abundant waste steams generated in European cities impacting dramatically on environment, society, and economic sectors. A novel sustainable biotechnology is here proposed to produce marketable caproic acid from mixed WAS and FW with in-situ self-formed lactate without buffering agents addition. Different mix ratios between WAS and FW, and thermal pretreatment strategies were compared by fermentation batch tests. The production of lactate as electron donor (ED), together with acetate and butyrate, and hydrogen assured high production of caproate only in presence of thermal pretreated WAS, able to reduce the potential risk of lactate accumulation and drop in pH. The findings of this study demonstrate that the initial soluble carboydrate/protein ratio significantly affected the pH of the fermentation broth in the first hours of fermentation, and that only using FW and pretreated WAS mixed using a ratio of 60/40 in terms of volatile solids, CE pathway and lactate utilization as ED were promoted obtaining the highest percentage of caproate (about 21% of the total produced carboxylic acids; 2 gCOD/L).

LCA and LCC of wire arc additively manufactured and repaired parts compared to conventional fabrication techniques

Multi-material wire arc additive manufacturing (MM-WAAM) exhibits considerable promise for producing functional gradient materials, components with complex design, and enable a more local supply chain. However, it is still to be determined for which industrial applications MM-WAAM present more benefits than conventional production routes both in terms of environmental and economic impacts. This study undertook a comprehensive cradle-to-grave assessment encompassing two distinct metallic components, manufactured via either additive manufacturing (AM) or conventional fabrication procedures. One of those is a repair case of a forging die, and the other is the production of an industrial tool. Analysis outcomes manifestly revealed pronounced benefits associated with MM-WAAM for these components. For instance, the utilization of MM-WAAM in crafting an optical fiber case injection mould tool yielded energy consumption reduction, attributed to enhanced conformal cooling channels. Additionally, the repair of a forging die via MM-WAAM showcased the potential to curtail new scrap generation during post-processing, prolonging tool lifespan. This study conclusively shows the application-specific nature of MM-WAAM's favourability over traditional processes, thereby offering valuable insights for strategic implementation.

Holistic Assessment of Decarbonization Pathways of Energy-Intensive Industries Based on Exergy Analysis

The decarbonization of the industrial sector plays a crucial role in a successful energy transition. This transformation is very costly and complex, as many of the existing production processes and plants will have to be partially or completely replaced to reduce carbon dioxide (CO2) emissions. This raises questions about how significant reductions in CO2 emissions resulting from decarbonization will affect the use of resources to produce a certain product and the overall value of sustainability. This article considers the relationship between CO2 reduction and the impact on the resource efficiency of an industrial production process. For this purpose, a methodology was developed that holistically assesses the decarbonization pathway of an industrial sector. This holistic assessment takes into account the energy carriers, raw materials, and auxiliary and construction materials used for the operation and building of the significant plant components and summarizes them as a total use of resources. For this purpose, the use of resources is represented by the thermodynamic quantity exergy, which takes into account both the energy and material components of a production process. The energy and material streams in a production process are balanced by applying exergetic analysis. This methodology is used for current state-of-the-art and future decarbonized production processes in order to quantify the effects of the decarbonization process. By comparing the calculated resource efficiencies, the thermodynamic impact on the sustainability of decarbonization paths can be set in relation to the amount of CO2 saved. For validation, the developed methodology is applied to a conventional and a decarbonized ammonia production process. The conventional production route represents the production of ammonia by methane steam reforming, and the decarbonized production route is represented by synthesis gas production via water electrolysis and an air separation unit. The resource efficiency of the conventional ammonia production route, taking into account the energy sources, raw materials, construction materials, and auxiliary materials used, is 59%, producing a total of 1539 kg of CO2 emissions per ton of ammonia. The decarbonized process has a resource efficiency of 45%, while no CO2 emissions are produced in this manufacturing process. This means that the decarbonization of the production process reduces resource efficiency by 14%. In relation to the reduced amount of CO2, specific resource efficiency decreases by 9.09%/tCO2. The decline in resource efficiency is mainly due to the high level of heat and energy recovery in the conventional process and the very electricity-intensive hydrogen production in the decarbonized production process.

Electrochemical Cells for Novel Routes to Ammonia

Ammonia is an extremely important chemical compound. Annual production exceeds 180 million tons of which ~80% is used for fertilizer production. The conventional production route is CO2 intensive and almost 2% of global anthropogenic CO2 emissions stems from ammonia synthesis. This will have to change over the coming decades to ensure the politically targeted emission reductions.The synthesis gas a mixture of N2 and H2 will have to be produced in a green and sustainable manner eventually only relying on green power and sustainable synthesis routes as discussed in [1]. High temperature electrochemical cells can play a role in this, not only for providing a green stream of hydrogen, but also in realizing the required N2 as discussed in [2]. Here, a special mode of operating an SOEC was proposed including feeding some air together with the steam to the SOEC cathode to produce directly a N2/H2 mixture suitable for down-stream ammonia synthesis. This can be done with excellent efficiency [2].Here, we shall present a different and in several aspects advantageous route for providing N2 for green ammonia synthesis. It is suggested to produce the N2 by electrochemical pumping the oxygen out of an air stream. The overall energy efficiency of the concept will be discussed in detail. However, the motivation to pursue this route relies on that it would be applicable on “small” scale. Considering the scale of renewable electricity sources it would be advantageous if also ammonia synthesis could be scaled down to match the small scale and distributed nature of renewable electricity generation. Here, a technology that scales just like the electrochemical routes to be applied for the Hydrogen production would be advantageous. Whereas cryogenic distillation is an energy efficient route to provide N2 it is a technology, that would not scale down well.A solid oxide cell for electrochemical production of N2 by oxygen extraction from air was developed. 5*5 cm pieces were prepared and characterized both with respect to electrochemical performance and long term durability as tracked over 2000 hr. The cells are based on a ~10 micron CGO (Ce0.9Gd0.1O2) electrolyte sandwiched between composite supports (electrodes) made in either LSCF/CGO, or LSF/CGO. (LSCF=La0.6Sr0.4Co0.2Fe0.8O3- δ , LSF= La0.6Sr0.4FeO3- δ). To boost performance at low temperature the electrodes were infiltrated with Pr-oxide [3]. The performance with the different supports is compared at a range of temperatures and current densities with and without infiltration. Both materials were found to perform well and enable current densities ~0.8 A/cm2 at ~ 150 mV polarization, when tested at 700 oC. A 90% pure N2 stream can be produced with at a cell voltage below 150mV at temperatures from 700-800 ºC. As illustrated in Fig. 1, a purer N2 stream with 96% N2 could be produced at a cell voltage below 200 mV. Also a 98% pure N2 stream was demonstrated. Moreover, the cells were demonstrated to operate without degradation over a 2000 hr. period.The results are quite promising in terms of the excellent durability demonstrated and in terms of absolute energy consumption. For comparison with literature, the energy consumption is related to the removed oxygen rather than the produced N2. At 150 mV the energy consumption is ca. 0.7 kWh/m3 of oxygen extracted. This compares well with performance reported by Wang et al. [4] describing a similar concept. The energy consumption is ca. twice what it takes to produce the oxygen via cryogenic distillation. Here, it should be noted, however, that all the produced heat (0.7 kWh/m3) can be directly utilized in synthesizing the H2 needed for the ammonia due to the endothermic nature of steam splitting. Hence, the energy invested in producing the N2 is not really wasted in this case, as also discussed in [2].The results of detailed electrochemical testing will be presented and the factors limiting cell performance will be discussed. Finally, an analysis of what dictates the optimal point of operation in terms of energy consumption and component volume and reliability is presented. Acknowledgment The work was supported by the EU commission via project; ARENHA, H2020 GRANT AGREEMENT: 862482. References Campion, N., Nami, H., Swisher, P. R., Hendriksen, P. V., & Münster, M. (2023). Renewable and Sustainable Energy Reviews, 173, 113057. 2022.John Bøgild Hansen and Peter Vang Hendriksen 2019 ECS Trans. 91 2455.Hendriksen, P. V., Khoshkalam, M., Tong, X., Tripkovic, D., Faghihi-Sani, M. A., & Chen, M. 2019 ECS Transactions, 91, 1413-1424.Mei Wang, Kamil Maciej Nowicki, and John Thomas Sirr Irvine, Journal of The Electrochemical Society, 2022, 169, 064509 Figure 1

Ammonia as an SOFC Fuel

The conventional production route of ammonia relies on natural gas as a source of hydrogen and is thus very CO2 intensive; almost 2% of global anthropogenic CO2 emissions stems from ammonia synthesis. This will have to change over the next two to three decades, where a “green route” to ammonia must be deployed to ensure required emission reductions.The annual production of ammonia is currently around 180 million tons of which ~80% is used for fertilizer production. This will likely increase due to increased fertilizer demand, but also because ammonia is a promising energy vector and a potential green fuel for the shipping sector. The expected energy demand for global shipping by 2050 is in the order of ~15 EJ [1]. It will be difficult to cover such a large demand by bio-mass derived fuels (e.g. methanol) considering global limitations in sustainable biomass resources and the needs of other sectors like aviation, heavy transport and chemical industry [1]. Hence, for the green transition efficient and sustainable routes to green ammonia are important, as will be efficient technologies to convert ammonia to electricity.Ammonia is an excellent fuel for SOFCs as previously reported in several studies [2], [3]. We have in the framework of the project “SOC4NH3” [3] investigated the impacts of firing an SOEC with ammonia in terms of its impact on overall losses, the cell degradation mechanisms as well as potential benefits.SOEC durability, when operating on ammonia, was followed over extended test periods between 2000 and 6000 hours at single cell level at different temperatures and current densities. The cells were Ni/YSZ-supported thin electrolyte cells of a 5*5 cm2 foot-print. The degradation rates observed when feeding with ammonia were very similar to degradation rates observed for the same cells when operated in a 1:3 gas mixture of N2/H2.Also the detailed electrochemical performance was explored at different temperatures using impedance spectroscopy. An example of impedance spectra obtained when feeding ammonia to the cell or a N2/H2 gas mixture at ca. 850 oC and 675 oC is presented in Figure 1. When feeding ammonia a cooling is observed due to the endothermic nature of the cracking reaction. This leads to a slight increase in both series resistance and polarization resistance. Therefore, the impedance responses in the ammonia experiments is in the Figure compared to responses obtained in N2/H2 at a slightly lower furnace set-point temperature (5-10 oC lower). Evidently, at around 850 oC, the only effect on the impedance response of feeding ammonia directly is the slight reduction in temperature; the N2/H2 and NH3 responses are practically identical when comparing characteristics at furnace set-point temperatures of 845 oC and 850 oC for N2/H2 and NH3, respectively. In contrast, if the same experiment is conducted at around 675 oC a difference between the response in ammonia and the response in N2/H2 is observed. The difference in behavior cannot be compensated by just lowering the furnace temperature a bit to simulate the impact of a cooling. The impedance at high frequency in ammonia is clearly much larger than for the N2/H2 feed. Note here, that the Rs in the two different feeds is practically identical. Hence, we have to conclude that there is a direct negative effect of the presence of ammonia at the electrode on the hydrogen oxidation kinetics. The effect is stronger than what can be ascribed to cooling and dilution of the H2. The details will be discussed in the paper.SOFC operation on ammonia and its impact at stack level was also explored. Potential advantages of ensuring that a part of the ammonia cracks inside the stack, as opposed to up-stream the stack, was addressed by modelling. Finally, a TSP1 SOFC stack from Topsoe A/S was operated with some internal ammonia cracking. The results will be presented and discussed to elucidate benefits and limitations in operating SOFC stacks with internal cracking of ammonia. Acknowledgment The work was supported by the EUDP-project SOC4NH3; Grant Agreement 64018-0546. References MarEfuel Project report; “Electro-fuels for long range maritime transport”, 2021. https://orbit.dtu.dk/en/projects/electro-fuels-for-long-range-maritime-transport, available from Orbit DTU. J.B. Hansen, J. Madsen, J.U. Nielsen, N. Christiansen, Proceedings European SOFC Fuel Cell Forum, Luzern, Switzerland (2010), and A. Hagen. Risø International Energy Conference 2007, Risø-R-1608(EN) 3. John Bøgild Hansen and Peter Vang Hendriksen 2019 ECS Trans. 91 2455. Figure 1

Electrochemical Cells for Novel Routes to Ammonia

Ammonia is an extremely important chemical compound. The conventional production route is CO2 intensive and almost 2% of global anthropogenic CO2 emissions stems from ammonia synthesis. This will have to change over the coming decades to reduce negative impact on the climate and ensure a green route to ammonia. Here, a novel way to provide the synthesis gas mixture for ammonia synthesis is suggested based on combining an SOEC to provide the hydrogen with a dedicated cell to provide also nitrogen for the process. This is suggested to be achieved by electrochemically pumping out oxygen from an air stream. Cells were successfully developed and characterized for this purpose. Exit streams with more than 98% nitrogen purity were documented and the developed cells were shown to be stable over test periods exceeding 3000 hours of operation.

Thermophilic caproic acid production from grass juice by sugar-based chain elongation

Medium chain carboxylic acids (MCCA) such as caproic acid have a plethora of applications, ranging from food additives to bioplastics. MCCA can be produced via microbial chain elongation using waste and side-streams as substrates, a process that can be more sustainable than conventional production routes. Most chain elongation studies have focused on mesophilic conditions, with only two recent studies hinting at the possibility of thermophilic chain elongation, but a systematic study of its mechanisms is lacking. Here, we investigated thermophilic chain elongation from grass juice, to understand the effect of key operational parameters (pH, temperature, substrate) on the process performance and to establish the key microbial genera and their role in the system. The genus Caproiciproducens was identified as responsible for thermophilic chain elongation, and caproic acid production was most favorable at pH 6.0 and 50 °C among the conditions tested, reaching an average concentration of 3.4 g/L. Batch experiments showed that the substrate for caproic acid production were glucose and xylose, while lactic acid led to the production of only butyric acid. Fed-batch experiments showed that substrate availability and the presence of caproic acid in the system play a major role in shaping the profile of thermophilic chain elongation. The increase of the total sugar concentration by glucose addition (without changing the organic load) during continuous operation led to a microbial community dominated (75 %) by Caproiciproducens and increased by 76 % the final average caproic acid concentration to 6.0 g/L (13 gCOD/L) which represented 32 % (g/g) of the total carboxylic acids. The highest concentration achieved was 7.2 g/L (day 197) which is the highest concentration reported under thermophilic conditions thus far. The results of this work pave the way to the potential development of thermophilic systems for upgrading various underexplored abundant and cheap sugar-rich side-streams to caproic acid.

Special Issue “Novel Developments in the Bioproduction of Biochemicals and Biomaterials”

Bioprocesses with new environmentally friendly approaches, along with new perspectives that favor a transformation from conventional production routes to sustainable alternatives, as envisioned in the UN 2030 Agenda for Sustainable Development, will play an important role in the near future [...]

Finite element simulation of plasticity and fracture for Inconel 718 deposited by laser powder bed fusion – Chances, use and challenges

Laser Powder Bed Fusion (LPBF), is used to produce a component in layers by selective re-melting of a metal powder bed. A powder layer of an alloy is applied to a metal substrate within a process chamber filled with an inert gas. This powder layer is locally heated by a laser to a temperature above the melting point of the used alloy. Only regions of the applied powder which belong to the desired component are treated by the laser beam. After heating the layer is complete, the build platform is lowered by 30–90 µm and a new powder layer is applied. The procedure is repeated until the part is completed. After suitable post processing the part can be used. The relative density of the finished component is close to 100%. Depending on the deposition system the laser spot diameter measures approximately 40–80 µm, therefore the size of the resulting melt region is relatively small while cooling rates and temperature gradients are very high. Hence some resulting material properties of certain laser-melted alloys differ from the properties which can be achieved by conventional production routes. Furthermore, studies show that adjustment of certain process parameters can be used to influence the material condition, e.g., the anisotropy of the mechanical material properties. On the one hand this degree of freedom might offer opportunities to realize designed component properties, but on the other hand the modeling of the material condition and the resulting mechanical properties is challenging. A testing program covering different stress states as well as different material orientations has been performed at COMTES FHT. The tests revealed a significant orthotropy of plasticity and fracture which both are considered in the derived material card for the material model MF GenYld+CrachFEM – a material model developed by MATFEM. A good agreement between physical tests and finite element simulations of the performed tests was found. Chances and challenges in using the full potential of AM deposited materials based on detailed numerical modeling considering material orthotropic behavior are presented here for Inconel 718 and are supported by experimental testing.

Role of solvent in enhancing the production of butyl levulinate from fructose

The use of alkyl levulinates is growing interest in fuels. Adding n-butyl levulinate (BL) to fuels presents some benefits compared to ethyl levulinate. The conventional production route of BL is from the esterification of levulinic acid, but the latter compound presents some corrosion issues. Alcoholysis of fructose by butanol over cation exchange resins (solid catalyst) seems to be a better alternative. The effect of water addition, solvent, swelling effect (from the cation exchange resin), and fructose solubility at temperatures higher than 25 °C are unclear on this reaction. To understand these effects, the alcoholysis of fructose by butanol at 110 °C in different solvents, e.g., gamma-valerolactone (GVL), were studied in a pressurized autoclave in an inert environment. The dissolution study was conducted in a temperature range of 20–120 °C in different solvents. The concentration profiles of fructose, 5-(hydroxymethyl)furfural (HMF), 5-(butoxymethyl)furfural (BMF) and BL were analyzed in different solvents: butanol/water, butanol, butanol/GVL/water and butanol/GVL. We found that using a butanol/GVL (70/30 wt%) solvent is better from the conversion and dissolution viewpoints.

One‐step production of polyelectrolyte nanoparticles

AbstractNeutral polymeric nanoparticles have found many important applications in fields such as drug delivery, biosensing and environmental research. However, charged polymeric nanoparticles have not yet found such success mainly due to the multi‐step and time‐consuming conventional production route. An emulsification–evaporation method was described as a fast and reproducible way to obtain neutral polymeric nanosuspensions. We propose here, for the first time, to extend this method to the one‐step production of negatively charged polymeric nanoparticles. For this purpose, we compared different processes, namely sonication, shear mixing and elongational‐flow micromixing (μRMX), in order to produce polyelectrolyte nanoparticles (PNPs) of poly(styrene sulfonate). We found that only μRMX allowed the production of highly monodispersed PNPs. We also verified the decrease of nanoparticle size (from 300 to 150 nm) and polydispersity index by increasing the emulsification time and decreasing the polymer molecular weight. Finally, we observed and explained the causes of an unusual behavior: the sudden increase of PNP size after a given emulsification time when using μRMX. © 2021 Society of Chemical Industry

Gas Phase Catalytic Hydrogenation of C4 Alkynols over Pd/Al2O3

Alkenols are commercially important chemicals employed in the pharmaceutical and agro-food industries. The conventional production route via liquid phase (batch) alkynol hydrogenation suffers from the requirement for separation/purification unit operations to extract the target product. We have examined, for the first time, the continuous gas phase hydrogenation (P = 1 atm; T = 373 K) of primary (3-butyn-1-ol), secondary (3-butyn-2-ol) and tertiary (2-methyl-3-butyn-2-ol) C4 alkynols using a 1.2% wt. Pd/Al2O3 catalyst. Post-TPR, the catalyst exhibited a narrow distribution of Pdδ- (based on XPS) nanoparticles in the size range 1-6 nm (mean size = 3 nm from STEM). Hydrogenation of the primary and secondary alkynols was observed to occur in a stepwise fashion (-C≡C- → -C=C- → -C-C-) while alkanol formation via direct -C≡C- → -C-C- bond transformation was in evidence in the conversion of 2-methyl-3-butyn-2-ol. Ketone formation via double bond migration was promoted to a greater extent in the transformation of secondary (vs. primary) alkynol. Hydrogenation rate increased in the order primary < secondary < tertiary. The selectivity and reactivity trends are accounted for in terms of electronic effects.

Recent Progress in the Joining of Titanium Alloys to Ceramics

The prospect of joining titanium alloys to advanced ceramics and producing components with extraordinary and unique properties can expand the range of potential applications. This is extremely attractive in components for the automotive and aerospace industries where combining high temperature resistance, wear resistance and thermal stability with low density materials, good flowability and high oxidation resistance is likely. Therefore, a combination of distinct properties and characteristics that would not be possible through conventional production routes is expected. Due to the differences between the coefficients of thermal expansion (CTE) and Young's modulus of metals and ceramics, the most appropriate methods for such dissimilar bonding are brazing, diffusion bonding, and transient liquid phase (TLP) bonding. For the joining of titanium alloys to ceramics, brazing appears to be the most promising and cost-effective process although diffusion bonding and TLP bonding have clear advantages in the production of reliable joints. However, several challenges must be overcome to successfully produce these dissimilar joints. In this context, the purpose of this review is to point out the same challenges and the most recent advances that have been investigated to produce reliable titanium alloys and ceramic joints.

Energy-Efficient Routes for the Production of Gasoline from Biogas and Pyrolysis Oil-Process Design and Life-Cycle Assessment.

Two novel routes for the production of gasoline from pyrolysis oil (from timber pine) and biogas (from ley grass) are simulated, followed by a cradle-to-gate life-cycle assessment of the two production routes. The main aim of this work is to conduct a holistic evaluation of the proposed routes and benchmark them against the conventional route of producing gasoline from natural gas. A previously commercialized method of synthesizing gasoline involves conversion of natural gas to syngas, which is further converted to methanol, and then as a last step, the methanol is converted to gasoline. In the new proposed routes, the syngas production step is different; syngas is produced from a mixture of pyrolysis oil and biogas in the following two ways: (i) autothermal reforming of pyrolysis oil and biogas, in which there are two reactions in one reactor (ATR) and (ii) steam reforming of pyrolysis oil and catalytic partial oxidation of biogas, in which there are separated but thermally coupled reactions and reactors (CR). The other two steps to produce methanol from syngas, and gasoline from methanol, remain the same. The purpose of this simulation is to have an ex-ante comparison of the performance of the new routes against a reference, in terms of energy and sustainability. Thus, at this stage of simulations, nonrigorous, equilibrium-based models have been used for reactors, which will give the best case conversions for each step. For the conventional production route, conversion and yield data available in the literature have been used, wherever available.The results of the process design showed that the second method (separate, but thermally coupled reforming) has a carbon efficiency of 0.53, compared to the conventional route (0.48), as well as the first route (0.40). The life-cycle assessment results revealed that the newly proposed processes have a clear advantage over the conventional process in some categories, particularly the global warming potential and primary energy demand; but there are also some in which the conventional route fares better, such as the human toxicity potential and the categories related to land-use change such as biotic production potential and the groundwater resistance indicator. The results confirmed that even though using biomass such as timber pine as raw material does result in reduced greenhouse gas emissions, the activities associated with biomass, such as cultivation and harvesting, contribute to the environmental footprint, particularly the land use change categories. This gives an impetus to investigate the potential of agricultural, forest, or even food waste, which would be likely to have a substantially lower impact on the environment. Moreover, it could be seen that the source of electricity used in the process has a major impact on the environmental performance.

Effect of Sintering Method on Surface Fatigue of Carbide Composites

In this work the influence of sintering method on the surface fatigue of carbide composite was studied. The research focuses on WC-15wt%Co hardmetals prepared using different powders and different sintering techniques and as a result different microstructure: conventional WC+Co powder and novel reactive powder type W+C+Co are sintered using vacuum furnace, compression sintering (sinterhipping) and spark plasma sintering (SPS method). As tungsten carbide is a common material for cold forming punches and surface degradation causes punch failure [1], the tool life can be significantly extended by material surface fatigue life improvement. It is expected that SPS production route of WC-15wt%Co hardmetal will conclude in better microstructure, more even average grain size distribution and smaller residual porosity, and respectively better mechanical and surface fatigue properties compared to conventional production routes. There are some expectations related to the reactive sintering production routes, as this technique promotes the fine microstructure and better mechanical properties.

Methanol and dimethyl ether from renewable hydrogen and carbon dioxide: Alternative fuels production and life-cycle assessment

In this work we investigate two renewably based alternative fuels; methanol and dimethyl ether. The ultimate feedstocks for production are wind-based electrolytic hydrogen and carbon dioxide captured from an ethanol fermentation process. Dimethyl ether production was modeled in ASPEN Plus using a previously simulated methanol production facility. The facilities use 18.6 metric tons (mt) of H2 and 138.4 mt CO2 per day. Methanol is produced at a rate 96.7 mt/day (99.5 wt%) and dimethyl ether is produced at a rate of 68.5 mt/day (99.6 wt%). A full comparative life-cycle assessment (cradle-to-grave) of both fuels was conducted to investigate their feasibility and sustainability. Renewable methanol and dimethyl ether results were independently compared and this renewable process was also compared to conventional production routes. Results show that production of dimethyl ether impacts the environment more than methanol production. However the combustion of methanol fuel evens out many of the emissions metrics compared to dimethyl ether. The largest environmental impact was found to be related to the fuel production stage for both fuels. Both biofuels were shown to be comparable to biomass-based gasification fuel production routes. Methanol and dimethyl ether from CO2 hydrogenation were shown outperform conventional petroleum based fuels, reducing greenhouse gas emissions 82–86%, minimizing other criteria pollutants (SOx, NOx, etc.) and reducing fossil fuel depletion by 82–91%. The inclusion of environmental impacts in feasibility analyses is of great importance in order to improve sustainable living practices. The results found here highlight the favorable feasibility of renewably produced methanol and dimethyl ether as alternative fuels.

Evolution of microstructure, texture and inhibitor along the processing route for grain-oriented electrical steels using strip casting

In the present work, a regular grade GO sheet was produced successively by strip casting, hot rolling, normalizing annealing, two-stage cold rolling with intermediate annealing, primary recrystallization annealing, secondary recrystallization annealing and purification. The aim of this paper was to characterize the evolution of microstructure, texture and inhibitor along the new processing route by comprehensive utilization of optical microscopy, X-ray diffraction and transmission electron microscopy. It was found that a fine microstructure with the ferrite grain size range of 7–12μm could be obtained in the primary recrystallization annealed sheet though a very coarse microstructure was produced in the initial as-cast strip. The main finding was that the “texture memory” effect on Goss texture started on the through-thickness intermediate annealed strip after first cold rolling, which was not similar to the “texture memory” effect on Goss texture starting on the surface layers of the hot rolled strip in the conventional production route. As a result, the origin of Goss nuclei capable of secondary recrystallization lied in the grains already presented in Goss orientation in the intermediate annealed strip after first cold rolling. Another finding was that fine and dispersive inhibitors (mainly AlN) were easy to be produced in the primary recrystallization microstructure due to the initial rapid solidification during strip casting and the subsequent rapid cooling, and the very high temperature reheating usually used before hot rolling in the conventional production route could be avoided.