Time-temperature Conditions Research Articles

Self-healing performance and prediction model of microcapsule asphalt

Asphalt is a kind of material with self-healing ability, but the rate of self-healing can not repair the damage under real load in time. Microcapsule technology is considered to be an effective technology to improve the self-healing ability of asphalt. Clarifying the self-healing behavior of microcapsule asphalt and quantitatively evaluating the improvement effect are the premise of further practical application of microcapsule technology. In this study, a fatigue-healing-fatigue test was performed using a dynamic shear rheometer. The ratio of dynamic modulus decay rate before and after asphalt healing (HI) was employed to evaluate the self-healing performance of microcapsule asphalt. In addition, the fatigue-healing-fatigue tests of microcapsule asphalt with different damage degree, microcapsule content and asphalt type were carried out under different rest time and healing temperature conditions; The test results showed that HI increased nonlinearly with the increase of rest time, healing temperature and microcapsule content, and HI decreased nonlinearly with the increase of damage degree. Then, based on the polymer self-healing theory, a macro self-healing behavior model of microcapsule asphalt considering two-stage healing process was established, which can accurately predict the macro healing ability of microcapsule asphalt. Finally, the micro mechanism of repairing asphalt microcracks by microcapsules was obversed via fluorescence microcopy.

Modeling the pressure–temperature–time evolution of in situ shock veins: A terrestrial case study from Vredefort

AbstractNumerical computing software (via MathWorks MATLAB) has been developed to understand the relationship between shock wave passage in geological targets (i.e., heterogeneous media) and the formation of shock veins and associated high‐pressure/temperature polymorphs. This approach takes into consideration the pressure due to the passage of the shock front, subsequent rarefaction unloading pressures, and associated heating and cooling rates. The model is applied to calculate pressure–temperature–time conditions for coesite‐ and stishovite‐bearing shock veins within metaquartzites of the Vredefort impact structure of South Africa. To constrain the model, the position of the host metaquartzites at the time of impact is first reconstructed. The developed code then passes the appropriate shock conditions through the target to re‐create the shock wave, while simultaneously forming and cooling the shock veins via 2‐D steady‐state conduction. We have found that (1) at the time of shock vein formation (2.4 s following the initial contact of the projectile), the shock front pressure was 13.8 GPa and the width of the shock wave was of 27 km; (2) the melt within the shock veins initially reached ~3000 °C, which corresponds to the melting temperature of the target rock at 13.8 GPa. Simulation results indicate that conditions reach the stishovite stability field within 2 ms of vein formation (~10–14 GPa; 2000–3000 °C), followed by coesite within 1.29 s (~3–10 GPa; 600–2000 °C). The dwell time of the modeled shock vein system is 4.35 s. The shock vein system is completely solidified 33.4 s after the initial shock front passage. The calculated P–T–t path of the model indicates that the polymorphs within the shock veins of the metaquartzites at Vredefort formed under their normal stability field conditions following rarefaction wave decompression.

A calibrated empirical method to choose A factors for kerogen kinetics. Part 1: Using Easy%Ro to calculate thermal stress

Kinetic parameters (A factor and Ea distribution) for kerogens are routinely determined using data from high-temperature pyrolysis experiments, with few efforts to validate or calibrate the application of those high-temperature kinetics under cooler geological conditions. This study uses data from both natural and laboratory maturation to quantify thermal stress and thermal strain in source rocks. Values for both A and Ea are thus constrained under both laboratory and natural time-temperature conditions to make accurate predictions about thermal stress (quantified here as Ro-equivalent) and thermal strain (quantified as both Hydrogen Index and Mean activation energy (Mean Ea)). “Accuracy” is defined here as simultaneous agreement between measured values and values calculated using standard kinetic equations (Easy%Ro for thermal stress and the standard pseudo-first-order attrition hydrocarbon-generation model for thermal strain). To achieve this agreement the calculated A factor and Ea distribution for hydrocarbon generation were adjusted to fit the measured values for both stress and strain. The resulting solutions perform equally well under laboratory and natural time-temperature conditions.The method was developed and tested on nearly 2000 samples from ten North American kerogens representing various ages and kerogen types. If we assume that the 2001 equation of Jarvie et al. for converting Tmax to Ro-equivalent and that the Easy%Ro kinetics for evolution of Ro are satisfactory, the best single value for A for hydrocarbon generation is between 1e13 and 1.5e13 s−1, with a range from 1e13 to 5e13 among the best six data sets studied. The potential impact of using erroneous uncalibrated A factors in defining generation windows is demonstrated. This new information will lead to major increases in both the accuracy of modeling of hydrocarbon generation, and our confidence in the results of such modeling.

Au-catalyzed lateral Ga(In)AsP nanostructures grown in a quasi-closed cell

A new method for growth of Au-catalyzed lateral Ga(In)AsP nanostructures in a quasi-closed volume from a vapor source under semi-equilibrium conditions has been studied. Varied time-temperature conditions and nucleation modes were examined. It was found that lateral nanostructures elongated in the [11¯0] direction are formed on a (100) GaAs substrate at about 500 °C. Raising the growth temperature is accompanied by a significant change of the morphology of the nanostructures. The modified surface has a random textured structure with predominant pyramidal faceting. Changes in the alloy composition of the nanostructures were studied.

Влияние холодной деформации и термической обработки на структуру, текстуру и свойства титанового псевдо-β-сплава

The effect of cold plastic deformation and heat treatment on the phase composition, structure, texture, and mechanical properties of sheets of pseudo-β-titanium alloy VT35 has been studied. It has been established that after cold rolling of sheet semi-finished products, a multicomponent texture (111) + (112) + (100) is formed, which during subsequent heat treatment is transformed into a similar texture but with a lower degree of texturing. A generalized diagram of phase and structural transformations with temperature-time conditions for the onset of polygonization, recrystallization, and decay of the β-phase was constructed. It is shown that, subject to the sequence and kinetics of the processes occurring during heat treatment, it is possible to form a structure of various types in the alloy, which makes possible to change its technological and mechanical properties in a wide range.

Novel powder-XRD method for detection of acrylamide in processed foods

Acrylamide (AA) is a toxin in food systems associated with neurotoxicity, carcinogenicity, genotoxicity, and cardiotoxicity. While several approaches exist, this work details the first-of-its-kind application of Powder X-Ray Diffraction (PXRD) for the detection of AA in food systems. A new methodology was validated as per ICH guidelines. Various x-ray tube combinations such as current (25–45 mA), voltage (25–45 kV), and scanning parameters such as step size (0.006–0.10°) and time-per-step (50–150 s) were experimented on 10–80° angle 2theta (2θ). In this investigation, more diffracted peaks were detected on time per step 151.210 [s], 0.0135[°] step size @ 35 mA/45 kV through phase quantification. The developed method was successfully applied to real processed food samples for qualitative analysis of AA. In addition, the influence of oil frying temperature–time conditions on AA content was studied. Overall, this work highlights the prospects of PXRD-based food quality and safety evaluation.

Syrah Grape Skin Residues Has Potential as Source of Antioxidant and Anti-Microbial Bioactive Compounds.

Simple SummaryThe aim of this study was to verify the influence of different extraction parameters (temperature and ultrasound time) of bioactive compounds from the skin of the Syrah variety of grape. Among the extracts obtained, those exposed to 20 min of sonication had the best results in terms of flavonoid content, antioxidant potential and phenolic profile. The temperature of 60 °C provided the most relevant results for the content of total phenolics, stilbenes, flavonols and phenolic acids, however, the association of this temperature with the use of ultrasound showed lower results as a source of antioxidant and antimicrobial bioactive compounds.In this study, we evaluated the effects of ultrasound-assisted extraction (UAE) under different time-temperature conditions on the content of bioactive compounds, antioxidant and antimicrobial activities of Syrah grape skin residue. The application of UAE showed a positive effect on the extraction of total flavonoids, and a negative effect on total polyphenols. The temperature of 40 °C and 60 °C without the UAE caused an increase of 260% and 287% of the total polyphenols, respectively. Nineteen individually bioactive compounds were quantified. The anthocyanin concentration (malvidin-3,5-di-O-glucoside 118.8–324.5 mg/100 g) showed high variation, to a lesser extent for phenolic acids, flavonoids, flavonols, procyanidins and stilbenes due to the UAE process. The Syrah grape skin residue has a high concentration of total phenolic compounds of 196–733.7 mg·GAE/100 g and a total flavonoid content of 9.8–40.0 mg·QE/100 g. The results of free radical scavenging activity (16.0–48.7 mg/100 mL, as EC50) and its inhibition of microbial growth (0.16 mg/mL, as EC50 for S. aureus, and 0.04 mg/mL, as EC50 for E. coli) by grape skin extract (UAE 40:20) indicate high antioxidant and antibacterial activity. It was concluded that the use of ultrasound needs further analysis for its application in this context, as it has shown deleterious effects on some compounds of interest. Syrah grape skin residue has potential as a source of bioactive antioxidants, antimicrobial activity and for use as a functional food ingredient.

THE INFLUENCE OF COMPOSITION AND TECHNOLOGICAL FACTORS ON ADHESION STRENGTH OF FLUOROPLASTICS COATINGS TO METAL SURFACES

The ways of regulating adhesion of fluoroplastic coatings to metal surfaces are analyzed. It has been established that polymer and metal modification is necessary to increase the adhesive strength and resistance of fluoroplastic coatings. The relative impact of the nature of the metal on the strength of adhesive compounds of polymer – metal is less influenced by the nature of the polymer. The strength of metal compounds is significantly affected by the activation of the metal surface by mechanical treatment (grinding etc.). Various methods of oxidation, etching, metal phosphating are recommended to increase the adhesive strength of fluoropolymer coatings. Method of investigation of adhesion and resistance to scratch damage of coatings is given. The influence of composition and temperature-time conditions of the ground layer formation of the coating on adhesive strength of metal-polymeric compounds was investigated. Detailed operation modes are described. The properties of the ground layer of fluoropolymer Ф-30П are given. The peculiarities of the fluoroplastic coating ground layer formation are outlined. The technology of application of the fluoroplastic coating ground layer on electroplating of metal surfaces has been developed. The coating on the metal surface was done by electrostatic spraying of the ground layer powder at an electric field voltage of 50 kV. The deformation and strength properties of the unstabilized Ф-30П fluoroplast are found to be quite high, which together with high adhesive strength makes it possible to recommend this polymer as primer. It is also advisable to melt the ground layers in more rigid temeperature-time modes (melting temperature 2600 C, duration – 2 hours) in order to ensure higher adhesion strength. The adhesive strength of the Ф-30П fluoroplastic coating can be increased by 10-15% by additional heating at a temperature of 2400 C for two hours. Analysis of the results showed that the resistance of fluoroplastic coatings based on Ф-30П to damage by scratching with an increase in the graphite content of C-1 from 15% to 25% increases by a factor of 2.11, and inserting to coating with 25 mas.% of C-1 graphite additional 3 mas. % of the aerosil-based amino-ergoholozenese – 3.16 times. The additional termoprocessing of these coatings increases the resistance to damage by scratching by 30 per cent. Recommendations on the use of research results for obtaining fluoroplastic coatings with high-adhesion to metal surfaces are given.

ABOUT TECHNOLOGICAL FEATURES OF PRODUCTION OF REINFORSING BARS FROM PEARLITE GRADE STEELS

Formulation of the problem. In the production of coiled rolled products from perlite grade steels, metallurgical enterprises encounter with the sorting of some batches of continuously cast billets or commercial products due to non-compliance with regulatory requirements. One of the alternative ways of using such blanks can be their reassignment for the production of thermally hardened reinforcing bars. In accordance with the edition of GOST 5781-82, it was possible to produce hot rolled reinforcing bars from steel grade 80C (carbon content 0,74…0,82 %), and according to TU 14-15-339-94 – thermally hardened with a carbon content of 0,50…0,85 % C. In world practice, reinforcing bars of a strength class similar to classes A800…A1000 (DSTU 3760:2019) are made mainly of high-carbon steels. The main type of stressed reinforcement in the EU, USA, Canada and Great Britain are rods with a nominal diameter of 26…40 mm of strength class 835…1030 MPa and 26…36 mm of strength class 1080…1230 MPa. An analysis of the requirements for reinforcing bars according to various regulatory documents shows that in the standards of Canada, the USA and the UK, the carbon content is not standardized, but according to the standards of Japan and Ukraine it is 0,45…0,80 % and 0,13…0,37 % respectively. According to the requirements of international standards, the minimum values of the yield strength and strength correspond to the reinforcing bar A800 (DSTU 3760:2019). Therefore, for the possibility of producing reinforcing bars from high-carbon steels, it is necessary to establish rational temperature-time conditions for heat hardening modes, which will ensure that the finished metal products comply with the requirements of DSTU 3760:2019. Purpose. Determine the influence of the parameters of the technology of thermal hardening on the features of the formation of the structure and mechanical properties of reinforcing bars made of steels with a carbon content of 0,50…0,90 %. Results. The possibility of producing reinforcing bars of strength classes А800 and А1000 from steels С56DВ, C70DВ, C80DВ and C82DВ (EN 16120-2:2017) using intermittent and interrupted quenching methods has been scientifically proven. In accordance with the results obtained, the industrial production of reinforcing bars of strength classes A800 and A1000 from these steels is expedient, since it will contribute to the improvement of technical and economic indicators in the production of coiled steel from perlite grade steels intended for high-strength products (cold-worked rebar, metal cord, bead wire, spring wire, reinforcing ropes, etc.). Based on the results of industrial experiments, a technical agreement was developed and approved for the production of pilot batches of thermally hardened reinforcing bars of strength classes A800 and A1000 from steels containing 0.50...0.90 % carbon.

Vacuum Gasification-Directional Condensation for Separation of Tellurium from Lead Anode Slime

Tellurium is the indispensable base material of semiconductors in solar panels. Traditional tellurium recycling, a highly complicated separation process, has exhausted reagents and energy sources whilst producing waste residue and water containing multitudinous heavy metal that is hugely harmful to the ecological environment. A clean and eco-friendly vacuum distillation-directional condensation treatment was investigated for its potential to recycle tellurium from tellurium-rich lead anode slime (TLAS). The optimal distillation temperature and response time conditions of 1173 K and 50 min were obtained based on a large number of experiments. Gasification results indicated that under the optimal conditions of distillation temperature 1173 K, constant temperature time 50 min, and system pressure 5–15 Pa, 92% of tellurium was volatilized and enriched into the condenser from TLAS. Condensate results revealed that 88% of elemental tellurium was directly recovered in the volatile matter. The appropriate gasification-condensation processes realized a clean utilization to extract tellurium and separate multi valuable metals effectively.

Probing the history of ultra‐high temperature metamorphism through rare earth element diffusion in zircon

AbstractThe extent to which solid‐state volume diffusion modifies rare earth element (REE) abundances in accessory minerals during high‐temperature metamorphism governs our ability to link recorded trace‐element compositions to particular thermal events. We model diffusion of REE in zircon under different temperature–time conditions and show that, for both short‐lived (e.g. 1100°C for 1–5 Ma) and more prolonged (e.g. 1050°C for 10–30 Ma or 1000°C for 200 Ma) episodes of ultra‐high‐temperature (UHT) metamorphism, REE diffusion in igneous zircon is sufficiently rapid for REE in a ~50‐μm grain to equilibrate with the new metamorphic mineral assemblage of the host rock. By contrast, unless diffusion is accelerated by recrystallization, the presence of fluids or other processes at temperatures below 900°C zircon will largely retain its original pre‐metamorphic REE abundance pattern, even when the thermal event is long lived (≥100 Ma). Where volume diffusion is dominant, for instance, in the absence of a fluid phase, the sensitivity of REE mobility to temperature can help constrain the temperature–time path of high‐grade metamorphic rocks. Modelling of well‐characterized natural samples from the regional‐scale aureole surrounding the Rogaland Igneous Complex (RIC) in SW Norway shows that variations in REE concentration patterns in zircon indicate a T–t evolution that is consistent with independent P–T–t estimates for regional metamorphism based on phase equilibrium modelling (850–950°C at 7–8 kbar for ~100 Ma). Greater modification of REE abundance patterns in zircons within 2 km of the RIC contact, however, indicates that UHT conditions persisted for ~150 Ma close to the intrusion, with a temperature of ~1100°C for 1–5 Ma at the RIC contact. Thermal modelling suggests that the inferred T–t histories of samples from different distances from the RIC contact are best explained if the complex was emplaced incrementally over 1–5 Ma.

Towards a more efficient Hydrothermal Carbonization: Processing water recirculation under different conditions.

The use of Processing Water (PW) on the Hydrothermal Carbonization (HTC) of tunisian pine cones was investigated under different temperature (200 and 240°C) and residence time conditions (3 and 20h). Recirculating PW improved the HC (hydrochar) solid yield, without being detrimental to the carbon content of the HC. The heating value of the HCs, that with a single reaction already involved a rise of this parameter in the range 22.1-55.8% as compared to the raw material, was further increased up to 24.9-58.6% for cyclic runs. This was attributed to enhanced secondary char formation by reusing liquid, although this effect depended on the severity of previous HTC and was affected by both temperature and time. The HCs showed an increment on C and especially on N for cyclic runs. Also, thermal degradation peaks during HC TGA/DTA analyses showed a broader temperature range decomposition upon pyrolysis when PW was recirculated. The modifications of HC surface morphologies and functional groups was also investigated and associated to related reaction mechanisms.

Single Origin Coffee Aroma: From Optimized Flavor Protocols and Coffee Customization to Instrumental Volatile Characterization and Chemometrics.

In this study, the aroma profile of 10 single origin Arabica coffees originating from eight different growing locations, from Central America to Indonesia, was analyzed using Headspace SPME-GC-MS as the analytical method. Their roasting was performed under temperature–time conditions, customized for each sample to reach specific sensory brew characteristics in an attempt to underline the customization of roast profiles and implementation of separate roastings followed by subsequent blending as a means to tailor cup quality. A total of 138 volatile compounds were identified in all coffee samples, mainly furan (~24–41%) and pyrazine (~25–39%) derivatives, many of which are recognized as coffee key odorants, while the main formation mechanism was the Maillard reaction. Volatile compounds’ composition data were also chemometrically processed using the HCA Heatmap, PCA and HCA aiming to explore if they meet the expected aroma quality attributes and if they can be an indicator of coffee origin. The desired brew characteristics of the samples were satisfactorily captured from the volatile compounds formed, contributing to the aroma potential of each sample. Furthermore, the volatile compounds presented a strong variation with the applied roasting conditions, meaning lighter roasted samples were efficiently differentiated from darker roasted samples, while roasting degree exceeded the geographical origin of the coffee. The coffee samples were distinguished into two groups, with the first two PCs accounting for 73.66% of the total variation, attributed mainly to the presence of higher quantities of furans and pyrazines, as well as to other chemical classes (e.g., dihydrofuranone and phenol derivatives), while HCA confirmed the above results rendering roasting conditions as the underlying criterion for differentiation.

Influence of deformation at elevated temperatures on stability of microstructure and mechanical properties of UFG aluminum alloy

Ultrafine-grained (UFG) state with a mean grain size of 180 nm was produced in a 6060 alloy of the Al-Mg-Si system by high pressure torsion (HPT). The UFG Al 6060 alloy demonstrated high strength: microhardness of 120 Hv and ultimate tensile stress of 525 MPa at room temperature. The tensile tests were carried out at temperatures 120, 150 and 180 °C with the strain rate 10−2, 5 × 10−3, 10−3, 5 × 10−4 and 10−4 s−1 to determine the best conditions for the manifestation ductility and study of changes in strength of the study material. It established, that the UFG alloy retains an increased 80% of level of strength at room temperature after deformation at elevated temperatures in the temperature range 120–150 °C. The results obtained are compared with changes of the microstructure and strength of the UFG alloy after annealing under similar temperature–time conditions.

Influence of temperature-time crystallization conditions on PP + ZrO2 charge state and electret properties

PP + ZrO2 polymer nanocomposites obtained through different temperature-time modes of crystallization and exposed to electrothermopolarization were studied in this paper. Even though the preparation method of nanocomposite samples was the same, their lifetimes and surface charge density were different. It was investigated that nanocomposite obtained by slow-cooling (SC) conditions has high stability but low surface charge density. It was also revealed that the dependence of relaxation time of the electret state on the percentage content of filler has a nonmonotonic character. The change of the thickness of the interphase layer of nanocomposite depending on cooling rate is explained by the change of the supramolecular structure of the polymer and the interphase interaction among the components of the nanocomposite. It was considered that the change of the thickness of the interphase layer of the nanocomposite depending on the intensity of the electric field during electrothermopolarization due to the difference in charge accumulation during the polarization process.

The optimal time-temperature conditions for orange juice microwave−assisted pasteurization

In this work, the inactivation kinetics of pectin methylesterase (PME) and degradation kinetics of ascorbic acid (AA) of batch microwave-assisted pasteurized orange juice were studied, at time-temperature conditions from (70–90) °C between (0 and 180) s. The two-component first-order and the fractional kinetic models were adjusted for PME and AA data, respectively. The microwave treatment was effective for the inactivation of PME with minimal AA retention of 85%. The adjusted kinetics parameters at Tref = 90 °C, for PME were: D1, 90 °C = 0.18 s, D2, 90 °C = 32. 8 s, z1 = 10.6 °C, z2 = 11.8 °C, with α = 0.91. For AA were: k90 °C = 0.02 s−1 and z = 55.4 °C with AA∞/AA0 = 0.85. A time-temperature diagram created from the kinetics parameters indicates the best isothermal conditions for orange juice from 78 s at 82.5 °C to 18 s at 90 °C.

Using of mathematical methods in the study of temperature-time conditions of the arc surfacing upon manufacturing of steel-aluminum compositions

A mathematical model for studying temperature-time conditions of arc surfacing upon manufacturing of steel-aluminum compositions has been developed and verified. During simulation, the dependences of the thermophysical properties of the materials under study (thermal conductivity and heat capacity of a unit mass of the substance at constant pressure and volume) on the heating temperature were added to the database of the «SVARKA» software to solve the thermal problem. When simulating the arc surfacing, the geometric model of the object was set in the form of a single body, which, e.g., in case of formation of functional coatings based on non-ferrous alloys on steel substrates, can consist of various materials. The parameters of the heat loads of the heating source are: the advance speed, power, distribution along and across the weld, as well as the presence and grade of the filler material. The calculation of heat propagation upon argon-arc surfacing with a non-consumable electrode was carried out according to the scheme with a normal-circular heat source located on the surface of a flat layer with the limiting effect of the bottom plane of the sheet. The considered calculation scheme includes all the main features of the argon-arc surfacing process, i.e., introduction of the heat of the welding arc into a massive body from the surface; small pressure of the welding arc; slight immersion of the active arc spot in the liquid metal. It is shown that allowance for the thermophysical properties of the intermetallic layer of the Fe – Al system located in the diffusion zone, provided determination of the heating temperature with the uncertainty of no more than 8 % not only at the steel-aluminum interface, but also at any point of the samples both in the transitional bimetallic steel-aluminum elements joined with aluminum or steel structures, and in functional aluminum coatings formed by surfacing, including those made of composite materials.

Measurement of the Strength and Microstructural Characteristics of Epoxy Polymers Cured by Thermal and Microwave Methods

Epoxy polymer samples cured by thermal and microwave methods under different temperature-time conditions are studied. The physical and mechanical parameters of the epoxy polymer samples, as well as their microstructure and fractographic fracture patterns, are studied. A tensile test method is used is used to determine the dependence of their strength parameters on the curing regime. Optimal regimes are identified for both curing methods, which makes it possible to obtain samples with maximum strength. Electron microscopy is used for comparative fractographic analysis of the fracture surfaces of samples with similar strength characteristics with thermal and microwave curing. It is found that microwave curing yields an increased globule size and more nanopores, as well as more pronounced local plastic deformation during fracture, and a larger spread in the ratio of the propagation velocities of main and secondary cracks. The dependence of the optical density of the test samples on the thermal and microwave curing regimes is established for wavelengths of 360–2500 nm.

Kinetics of Pectin Reactions in Apple Pomace During Hydrothermal Treatment

The kinetics of pectin reactions in apple pomace were modelled preparatory to developing a time-temperature operating map for quantity and quality of solubilized pectin and other reactions in apple pomace. This graph can be used for selecting suitable time-temperature conditions for hydrothermal treatments to ensure a safe product with expected quality. Kinetics were measured for the major reactions in apple pomace heated at 90–140 °C for 0–210 min, in particular for the solubilization and depolymerization reactions of pectin. Maximum levels of soluble pectin (~ 605 μmol galacturonic acid/g dry pomace) were observed when heating pomace (diluted 1:2) at 130 and 140 °C for 15 and 7 min, respectively. Acid hydrolysis and β-elimination reactions showed temperature-dependent behaviour, with activation energies of 81 and 65 kJ/mol, respectively. Heating at temperatures ≥ 110 °C resulted in degradation of soluble pectin into ethanol-soluble galacturonic acid. Depolymerization reactions of pectin occurred at non-esterified sites within the pectin polymers, as suggested by the high degree of esterification of the remaining insoluble pectin.

A kinetic study of liquid gallium diffusion in a tin-based solder alloy and its role in solder embrittlement

A first quantitative analysis of the liquid gallium (Ga) embrittlement of a tin (Sn)-based solder alloy is reported here. Ga penetration into Sn96.5-Ag3-Cu0.5 (SAC305) solder was found to follow a diffusion-controlled process using simultaneous intergranular and transgranular paths. A model of the diffusion kinetics of liquid Ga into SAC305 solder thin films was established and appears to obey an Arrhenius relationship. Diffusivity in a 1000 nm thin film was found to be of the same order of magnitude (10–10 m2 s−1) as those determined for other systems of liquid metal penetration into solid metal at similar relative temperatures, i.e., close to the liquid metal melting point and significantly below the solid metal melting point. Determined activation energies in the range of 30–37 kJ mol−1 support a mixed grain boundary and lattice diffusion process that is consistent with the observed intergranular/transgranular penetration. This exponential temperature dependence of liquid Ga diffusion and resultant SAC solder degradation suggests that a liquid metal embrittlement-based solder rework process can be established under favorable time–temperature conditions.