Carbon contents design and characterization of gradient cemented carbonitrides with nano-TiN addition

Gradient cemented carbonitrides with brittle cubic phase depleted in the surface layer were prepared in the paper. This gradient material is believed to be a promising composite used as the substrate of a coated insert for machining operation. The formation of gradient layers stems from nitrogen decomposition. In this paper, nano-TiN was introduced as a nitrogen supplier, and besides it functioned as a grain growth inhibitor of (Ti,W)C cubic phase. The microstructure, fracture morphology, mechanical and magnetic properties of the gradient cemented carbonitrides with carbon contents from 6.04wt% to 6.34 wt% were investigated systematically. The results show that lattice parameters of (Ti,W)C in the transit zone increase due to more Ti solid solution when the gradient layer thickens. (Ti,W)C grains in the inner bulk are refined effectively by nano-TiN. Intergranular fracture along WC grain, transgranular fracture of (Ti,W)C grains, and the tearing of binder are found in the bulk of the gradient cemented carbonitride. When cracks encounter the gradient layer, they grow from new origins and a macroscopic boundary is formed between the gradient layer and the bulk. The transverse rupture strength is promoted with the carbon contents increased, and its stability is also increased. Additionally, the microhardness of the gradient cemented carbonitride is correlated closely with the Ti and Co distribution.     

热处理工艺对0Cr16Ni6不锈钢硬度的影响

硬度表征着材料抵抗外界变形的能力,是生产中检验材料性能的重要参数之一。采用不同热处理工艺对Ф60mm 0Cr16Ni6不锈钢棒料进行工艺试验,分析0Cr16Ni6钢的显微组织,研究不同热处理工艺对0Cr16Ni6钢硬度的影响规律,最终使0Cr16Ni6不锈钢硬度值达到了41～43HRC,满足了生产使用要求。     

低银Sn-Ag-Cu-Bi-Er焊料及其焊点的拉伸性能研究

采用差热分析、润湿性和力学性能试验研究了自主研发的一种新型低银无铅焊料Sn-XAg-0.3Cu-3Bi-0.05Er(SACBE)(X=1.0,1.5,2.0)及其焊点的拉伸性能。结果显示,与Sn-3.0Ag-0.5Cu(SAC)焊料相比,SACBE焊料具有较低的起始熔化温度(204～206℃)和较好的润湿性。Cu/SACBE/Cu焊点的拉伸强度与Cu/SAC/Cu焊点相当,但是其韧性显著改善。表明新型低银SACBE焊料,在保持SAC焊料优良物理力学性能基础上所具有的成本优势。     

Investigation of small Sn–3.5Ag–0.5Cu additions on the microstructure and properties of Sn–8Zn–3Bi solder on Au/Ni/Cu pads

The formation of intermetallic compounds and the shear strength of Sn–Zn–Bi solder alloys with various (0, 1, 3, 5 and 7 wt%) weight percentages of Sn–Ag–Cu were investigated on Au/Ni metallized Cu pads depending on the number of reflow cycles. In Sn–Zn–Bi solder joints, scallop-shaped AuZn₃ intermetallic compound (IMC) particles were found at the interfaces and in the solder ball regions, fine Bi- and needle-shaped Zn-rich phase were observed in the Sn matrix. After Sn–Ag–Cu additions, an additional Ag–Zn intermetallic compound layer was adhered to the top surface of the AuZn₃ layer at the interface and fine spherical-shaped AgZn₃ intermetallic compound particles were detected in the solder ball regions together with Bi- and Zn-rich phase volumes. After the addition of Sn–Ag–Cu, the shear strength of Sn–Zn–Bi solder joints increased due to the formation of the fine AgZn₃ intermetallic compound particles. The shear strengths of Sn–Zn–Bi and Sn–Zn–Bi/7 wt% Sn–Ag–Cu solder joints after one reflow cycle were about 44.5 and 53.1 MPa, respectively and their shear strengths after eight reflow cycles were about 43.4 and 51.6 MPa, respectively.     

去除废旧硬质合金表面TiN涂层的双氧水+草酸钾碱溶液配制研究

以废旧涂层硬质合金为实验材料,采用双氧水+草酸钾碱溶液去除硬质合金表面TiN涂层,研究了双氧水浓度、草酸钾浓度、pH值和反应时间等对TiN涂层去除效果的影响,得到了草酸钾和双氧水碱溶液的最佳配比,可以为工业生产提供参考。     

熔融NaOH去除废旧硬质合金表面涂层

采用NaOH与钠盐的熔融混合液去除废旧硬质合金刀片表面的Ti(C,N)+厚层α-Al2O3+超平滑表面层的复合涂层.目测试样表面颜色变化,用扫描电镜观察表面微观形貌,并通过能谱仪分析涂层表面成分,讨论熔液温度与保温时间刘涂层的去除效果以及回收的硬质合金质量的影响;进一步分析表面涂层的去除方式及机理.结果表明,采用NaOH与钠盐的熔融混合液可以有效地去除涂层硬质合金的表面涂层物,在700℃、40min条件下能完全去除涂层,且对基体的损伤不大,试样的质量损失率为3.32％.     

One-step gas phase sulfided NiFe coating as self-supporting electrode for high efficiency oxygen evolution reaction

The development of cost-effective oxygen evolution reaction (OER) electrocatalytic electrodes is one of the essential means of applying green hydrogen energy. Due to the complex steps in the anodic OER, the high overpotential hinders the kinetics of water splitting. In this paper, the sulfided NiFe coating was innovatively designed as a self-supporting OER electrode by high-velocity oxygen fuel (HVOF) spraying coupled with one-step gas phase sulfuration. The thickness of the NiFe coating is approximately 20 μm. After the sulfuration treatment, the surface of the NiFe coating is remolded into a uniform rock sugar-like structure, and simultaneously forms new NiS and Ni₃S₄ phases. The sulfided NiFe coating electrode shows relatively low overpotentials of 220 mV and 253 mV at the current density of 10 mA cm⁻² and 100 mA cm⁻², respectively, and the Tafel slope is as low as 28.6 mV dec⁻¹. The excellent electrocatalytic activity is mainly attributed to the synergistic effect of sulfides, the adsorption of OH⁻ by the Ni³⁺ in alkaline electrolyte, and the acceleration of O₂ separation by the S²⁻ through promoting the cleavage of O–O bonds. In addition, the sulfided NiFe coating electrode also has a small charge transfer resistance, and the potential stability is as high as 98.1% in the 70 h stability test. Therefore, the development of sulfided transition metal coating electrodes can provide a new idea for the large-scale industrialization of water splitting.     

Sn3.0Ag0.5Cu0.05Cr/Cu焊点界面IMC层热时效形貌及生长行为研究

研究了Sn3.0Ag0.5Cu0.05Cr焊料(SACCr)制成的Cu/Solder/Cu焊点在150℃时效0、168、500及1000 h下界面金属间化合物(IMC)层的形貌及生长行为,并与Sn3.0Ag0.5Cu(SAC)焊料的焊点进行了比较。结果表明,相对于SAC的焊点,SACCr中弥散或固溶分布的微量Cr延缓了焊点界面IMC层的生长。时效时间越长,Cr的阻抑效果越明显。150℃时效1000 h的Cu/SACCr/Cu焊点界面IMC层的平均厚度是Cu/SAC/Cu的45%,仅为5.13μm。     

Monitoring,analysis, and quantification of hydrogen from biomass and biowaste: A review

Hydrogen is called to play a crucial role in decarbonizing different sectors by meaningfully reducing their emissions. Hydrogen production from biomass and biowaste has recently gained momentum due to the high availability of the resource and maturity of thermochemical conversion technologies. However, hydrogen monitoring and purification is required to optimize the process and to meet end-point-applications specifications. This paper provides a comprehensive state-of-the-art on the hydrogen monitoring, analysis, and quantification techniques, with a focus on gas mixtures containing hydrogen. Precision, response time, stability, selectivity of the methods together with other key parameters namely poisoning, interaction with other gases, hydrogen concentration, operating conditions, are confronted. The need for fast and precise hydrogen quantification, especially in the case of complex gaseous mixtures and for high-grade hydrogen applications, together with the need of reliable standards and materials able to provide fast hydrogen adsorption-desorption cycles are the main challenges that arise from our analysis.