Coating processes that purely use collision pressure or impact force such as the aerosol deposition (AD) method and cold spray method have been attracting attention. These methods accelerate microparticles and ultrafine particles into a beam at velocities of several hundreds of m/s or more that impacts a substrate, thus forming dense films with good adhesion forces by only providing purely mechanical energy. It is thought that microparticles of metals and ceramics can thus be macroscopically bonded at room temperature while remaining in a virtually solid state. In fact, the AD method has been commercialized as an important coating process in the field of semiconductor fabrication equipment which has been confirmed to be able to form thin or thick dense films of ceramics with microcrystal structures on the scale of several tens of nm or less at room temperature that offer excellent electromechanical properties. This is called room temperature impact consolidation (RTIC), and is thought to have different principles of film growth from thermal spray coating and shock compaction techniques which obtain bonding by putting the raw material particles into a molten or semi-molten state. This paper describes the deposition mechanism of AD processes that use RTIC and the importance of this as a coating technique for the future.

If the volume fraction of quartz in traditional ceramics is higher than 10% then the use of Selsing’s formula is questionable. A model of two concentric spheres, in which the inner sphere is a quartz grain and its spherical cladding is glassy phase, is proposed. The development of the stress on the grain surface during cooling stage of the firing and its influence on the microcracking is described. The tensile tangential stress which is developed between the glass transformation temperature and β → α transition of quartz can be a source of the first microcracking. After this transition, the tangential stress becomes compressive. The radial stress on the grain surface, which is compressive before the β → α transition of quartz, turns into tensile after this transition as a steep change of 40–80 MPa (for 10–50% of quartz content). These changes are in a narrow temperature interval around the β → α transition of quartz passing through zero value and no cracks are expected. This is confirmed with acoustic emission (AE) and short recovery of Young’s modulus. When the β → α transition of quartz is finished and the temperature decreases, the creation of the cracks continues. The radial tensile stress on the grain and in its close vicinity reaches 100–180 MPa, consequently, circumferential cracks can be formed. This is indirectly confirmed with a decrease of Young’s modulus and weak AE activity.

For a proper operation, conventional gas sensors based on solid electrolytes usually require complex heating elements and temperature control systems to ensure the transfer of ions inside a solid electrolyte substrate. In this study, a positive temperature coefficient (PTC) ceramic was used for the first time as a heating source to successfully compose a self-thermostatic potential NO₂ gas sensor. Powered by a 12-V multi-batteries, the PTC ceramic can be quickly heated to and stabilised at 250°C to provide the necessary working temperature to the sensor. It was proved that this self-thermostatic sensor displays a high NO₂ sensitivity (84.60 mV/decade) toward 5–150 ppm NO₂ at different ambient temperatures. Meanwhile, it exhibits a high NO₂ selectivity, along with excellent repeatability and stability. This simple and effective method is a solution to the significant obstruction of traditional gas sensors with burdensome heating structures, allowing a broad application to various types of on-site gas detection.

We present a relationship between piezoelectric property and crystal structure in melilite-type crystals. Two independent piezoelectric constants, d₁₄ and d₃₆, increase and decrease with the polyhedral distortion, respectively. Based on this knowledge, single crystals made of strontium-substituted calcium magnesium silicate Ca₂MgSi₂O₇ (CMS) have been submitted to the Czochralski method, which made them grown. The CMS crystal has a high d₃₆; however, its transition temperature is around 85 °C. Therefore, the strontium substitution is conducted to decrease this phase transition temperature. A single crystal of strontium substituted CMS, with nominal chemical composition Ca_1.7Sr_0.3MgSi₂O₇ (CSMS30), shows no phase transition when temperature rises from room to melting temperature. Its piezoelectric d′₃₁ constant is 2.1 pC/N and its compressive strength is 830 MPa on crystal substrate with (ZXt)45° cut. The CSMS30 single crystal is a superior candidate material for pressure sensors at high operating temperatures.

A facile strategy to fabricate polyaniline-ferrite (PANI-MFe_nO_m, M = Cu, Y) nanocomposites with differing ferrite content via an in situ oxidative polymerization method has been reported. X-ray diffraction, scanning electron microscopy and ultraviolet–visible diffuse reflectance spectroscopy were employed to study the phase structure, morphology and optical properties of the samples. The photocatalytic activity of as-prepared photocatalysts is evaluated by the degradation of rhodamine B in aqueous solution under visible-light (420 nm < λ < 800 nm) irradiation. The results show that polyaniline-ferrite nanocomposites exhibit higher photocatalytic activity and stability than both the naked ferrite and pure PANI. Among these as-prepared photocatalysts, PANI-CuFe₂O₄ composites with a PANI-to-ferrite ratio of 1:1 possess the highest degradation rate. Its apparent rate constant is 0.081 min⁻¹, which is 3.71 times as much as that of pristine PANI (0.021 min⁻¹). The presence of synergic effect between PANI and ferrites is believed to play a vital role in affecting the photoactivity.

In this study, we investigated the influence of the addition of MgO powder to the alkali and alkaline-earth borosilicate (AEB) glass paste on acid durability and peel adhesion characteristics of Ag conductors formed on the alumina substrate with the AEB glass paste. It was determined that the addition of the MgO powder to the AEB glass paste promoted crystal precipitation during the firing process of the printed AEB glass thick-film on the substrate at 850 °C. By characterizing the acid corrosion behavior in a H₂SO₄ aq., the weight loss after immersion for the micro-crystallized AEB glass thick-film with the added MgO powder was reduced by approximately half compared with that of the AEB glass thick-film without the MgO powder. In addition, no cracks were observed on the film surface of the micro-crystallized AEB glass, whereas cracks appeared on the film surface of the non-crystallized AEB glass after the acid corrosion treatment. It is thought that micro-crystallization induced by the addition of MgO powder to the glass paste during the firing process is partly involved in improving the acid resistance of the AEB glass thick-film. During the peel adhesion test of the Ag conductor on the alumina substrate in a H₂SO₄ aq., the Ag conductor formed with the MgO powder-added AEB glass paste exhibited small deterioration of peel adhesion in comparison to the Ag conductor formed using the AEB glass paste without the MgO powder. These results suggest that the correlation between the improved acid durability and peel adhesion characteristics of the Ag conductor formed with the MgO powder-added AEB glass paste was related to the micro-crystallization of the AEB glass induced by the addition of MgO powder to the thick-film pastes during the annealing process at 850 °C.

The effect of acid and heat treatments on chemical durability was investigated for cathode ray tube (CRT) funnel glass. The acid and post-heat treatment suppressed the lead leaching from the CRT funnel glass in an acid solution remarkably due to the formation of a silica-like surface layer. Pb ions were, however, easily leached into alkaline solution after the acid and post-heat treatment. In addition, the dependencies of acid resistance on the conditions of acid treatment and on the temperature of heat treatment were investigated.

The decolorization of foam glasses made from green and amber glass cullets was attempted. It was found that the addition of silicon carbide (SiC) and zinc oxide (ZnO) as decolorizing agents was effective for the decolorization of both the foam glasses made from green and amber glasses. Therefore, the addition of SiC and ZnO was suitable for the decolorization of foam glass made from the mixture of green, amber and colorless glasses.

A 250 nm thick pure tin film was deposited on quartz substrates by vacuum evaporation of 99.9% pure tin metal. The films were heated in a two-step annealing sequence for 3 h at 200 and 3 h at 400 °C with an electric furnace to decrease their surface roughness. This process transformed the films into tin(II) oxide. Subsequently, the films were annealed at five temperatures for 3 h each: 600, 700, 800, 900 and 1000 °C. The crystal structure of the film on the quartz substrate was completely transformed into SnO₂ at 600 °C. With the increase of annealing temperature to 1000 °C, the size of the lattices appeared to decrease on the thin film. In addition, the annealing process led to the formation of pores on the surface, but the number of pores and the lattices volume decreased with increased annealing temperature. The optical properties of the thin film were characterized by the use of visible spectrophotometry which showed a high refractive index at around 2.08–2.27. Interestingly, the SnO₂ thin film with the highest refractive index at 2.27, which was obtained at 1000 °C, exhibited the lowest Urbach energy. Therefore, the SnO₂ thin film has a high potential for optical applications, especially in dielectric waveguides and solar cells.

As a new type of material, magnesium oxysulfate (MOS) cement shows advantages of fire resistance, low alkalinity, light weight, and good decorative value. However, the low strength of MOS cement limits its large-scale applications in civil engineering, strength can be increased by adding appropriate admixtures. By adding different dosages (1, 3, 5%) of nano-silica (NS) and silica fume (SF), this paper studied the effects of the dosages on the compressive strength and water resistance of MOS cement. The phase composition and microstructure of MOS cement hydration products were analyzed by X-ray diffraction and scanning electron microscopy. The hydration process and pore size distribution of MOS cement were measured by hydration heat release rate and mercury intrusion porosimetry. The results show that the use of NS and SF as admixtures can inhibit the direct hydration of MgO to form Mg(OH)₂ and promote the formation of the 5Mg(OH)₂·MgSO₄·7H₂O (5·1·7 phase), improve the strength and water resistance of MOS cement to a certain extent.