Interface fracture behavior of electroplated coating on metal substrate under compressive strain

The inducement of interface fracture is crucial to the analysis of interfacial adhesion between coating and substrate. For electroplated coating/metal substrate adhering materials with strong adhesion, interface cracking and coating spalling are difficult to be induced by conventional methods. In this paper an improved bending test named as T-bend test was conducted on a model coating system, i.e. electroplated chromium on a steel substrate. After the test, cross-sections of the coated materials were prepared to compare the failure behaviors under tensile strain and compressive strain induced by T-bend test. And the observation results show that coating cracking, interface cracking and partial spalling appear step by step. Based on experimental results, a new method may be proposed to rank the coated materials with strong interfacial adhesion.     

TiO_2光催化剂掺杂改性的研究新进展

TiO2作为一种重要的光催化剂,对其进行掺杂改性可以有效的提高光催化活性。本文通过介绍金属与非金属的单掺、共掺对其光催化活性的影响,综述了近年来TiO2光催化剂在掺杂改性方面的研究进展。提出TiO2光催化剂在改性过程中亟待解决的问题及其在实际应用中的发展。     

半胱氨酸亚金钠的理化性质及化镍金工艺研究

目的合成一种新型水溶性亚金配合物,并分析其应用于无氰镀金的可行性。方法以氯金酸为金液、半胱氨酸为配体,在弱碱性条件下合成半胱氨酸亚金钠,通过元素分析仪、红外光谱仪、紫外可见光谱仪、热重分析仪、电导率仪研究其理化性质。以温度、p H值和金质量浓度为变量,通过单因素试验分析它们对镀金的影响,通过正交试验获得适宜的镀金工艺条件。结果该产物的分子式为Na Au(Cys)2。该配合物的结构中,半胱氨酸里巯基和亚金进行配位并形成了很强的配位键,该配合物的特征吸收波长范围在205~210 nm。差热曲线和电导率值测定结果显示,该配合物在170℃以前的热稳定性较好,是典型的离子化合物。最佳的镀金工艺参数为:p H=2,金质量浓度2 g/L,温度45℃。在该条件下,镀层的结合力好,镀速可控,镀金效果良好。结论合成了新型水溶性亚金配合物,其理化性质稳定,有望用于无氰镀金工业领域。     

Surface modification of wood flour and its effect on the properties of PP/wood composites

The surface of wood flour used as reinforcement in PP/wood composites was successfully modified by benzylation in NaOH solution of 20 wt% concentration at 105 °C. The time of the reaction was changed between 5 and 360 min in several steps. The progress of modification was followed by the measurement of weight increase and by diffuse reflectance infrared spectroscopy (DRIFT). The structure of the wood was characterized by X-ray diffraction (XRD) and its surface tension was determined by inverse gas chromatography (IGC). PP composites containing 20 wt% filler were prepared from a PP block copolymer and the modified wood flour. The mechanical behavior of the composites was characterized by tensile testing. The majority of the active hydroxyl groups at the surface were replaced by benzyl groups in about 2 h under the conditions used. Further increase in reaction time did not influence the properties of the filler. Both the structure of the wood flour and its surface tension changed as an effect of modification. The reduction of surface tension led to significant changes in all interactions between the wood flour and other substances resulting in a considerable decrease of water absorption, which is the major benefit of this modification. All measured mechanical properties of the composites decreased slightly with increasing degree of modification. A detailed analysis of the results proved that the dominating micromechanical deformation process of these PP/wood composites is debonding, which is further facilitated by the decrease in the surface tension of the filler. Chemical modification of wood flour slightly improved processability and the surface appearance of the composites prepared with them and considerably decreased the water absorption of these latter.     

Permanently Mechanically Adjustable Photothermal Catalytic Spontaneous Double Cross-Linking Network Enables Durable and Stretchable Plant Skin-Like Materials

In cellulose-based plastics, as a type of thermoplastic and thermosetting materials, the excellent balance of mechanical strength and ductility poses a large challenge. To tackle this problem, a novel approach is devised to introduce reversible non-covalent ester cross-linking into dynamic covalent hydrogen-bonded polymer networks. However, the formation of ester bonds typically requires excess reactants and dehydrating agents, which is energy-intensive, environmentally harmful, and costly. To address these concerns, inspired by polyester-rich plant bark, a supramolecular composite material is developed. It can be dissolved and regenerated using a binary solvent system (choline hexanoate/choline chloride-oxalic acid). In water, this supramolecular composite material underwent self-healing and ester exchange reactions to form double-cross-linked networks, interfaced with photo-thermal catalysis promoting the reaction due to its high photo-thermal conversion efficiency (86.7%) and water evaporation rate (1.38 kg m⁻² h⁻¹). This enables the rapid and repeatable construction of durable and stretchable biomaterials. The mechanical properties of the supramolecular plastic can be adjusted by solar photo-thermal conditions of the synthesis environment. These materials exhibit high performance in solar water evaporation and have self-healing properties and are degradable, recyclable, and capable of eliminating their own adhesions.