China
Africa
Explore chapters and articles related to this topic
Metalforming Applications
Published in Jerry P. Byers, Metalworking Fluids, Third Edition, 2018
As an alternative to solvent degreasing, alkaline cleaners are being used. These cleaners can be applied through a dip bath, impingement spray, or a tumbling parts washer, among others. One advantage is that, unlike vapor degreasers, alkaline cleaners are also effective for water-diluted lubricants, even those that contain oil. Alkaline cleaners are often warmed to speed up the processes that cause residue removal.
Evaluating The Alternatives
Published in Joseph D. Edwards, Industrial Wastewater Treatment, 2019
It some cases you may change a process to eliminate the generation of an air pollutant and end up generating a water pollutant. This is the case if you change from solvent degreasing to aqueous cleaning. Now you have wastewater to worry about instead of spent solvent and have to weigh the alternatives.
Enhanced degradation of carbon tetrachloride by sodium percarbonate activated with ferrous ion in the presence of ethyl alcohol
Published in Environmental Technology, 2019
Ping Tang, Wenchao Jiang, Shuguang Lu, Xiang Zhang, Yunfei Xue, Zhaofu Qiu, Qian Sui
The widespread usage and improper disposal of organic chemicals have led to the severe contamination of soils and groundwater throughout the world [1]. Carbon tetrachloride (CT) was once frequently used as cleaning solvent, degreasing agent, refrigerant, and aerosol propellant, and was also applied in nuclear weapons production [2]. Due to the characteristics of its carcinogenicity, environmental persistence, and relatively high solubility in water (800 mg L−1 at 20°C) [3], CT is an onerous contaminant and results in widespread contamination of soil and groundwater, particularly at nuclear reservation sites. Therefore, the concentration of CT in drinking water has been regulated and set by the maximum contaminant level at 0.005 mg L−1 in the U.S.A [4] and 0.002 mg L−1 in China [5]; hence, it is critical to develop an effective technique for CT degradation in contaminated soil and groundwater.
On the influence of different superficial laser texturing on the deposition of powders through cold spray process
Published in Transactions of the IMF, 2018
A. Viscusi, A. Astarita, S. Genna, C. Leone
The surface preparation of the substrate is a critical key in the production of high performance coatings, especially when cold spray processes are adopted. Many surface treatments, based on chemical or mechanical modifications, have been developed in order to improve the coating adhesion. Although widely used, these techniques present several disadvantages. For instance mechanical treatment, such as grit paper or sand blasting,16,17 are usually adopted in order to remove contaminants and to control the desired level of surface roughness. However, they show difficulty in process and surface extension control or material contamination (i.e. powder residues). Moreover, large plastic deformations throughout the surface, resulting in compressive stress and potential cracks, can occur. On the other hand, traditional chemical treatment (solvent degreasing, acid pickling or alkaline etching followed by conversion coating, or anodising treatment) is undesirable since they have implications for operators’ health and environmental safety.18,19 Recently, the laser treatment was introduced as a promising alternative to the aforementioned methods. By way of the laser treatment, it is possible to clean or prepare a surface,20–22 realise grooves (i.e. laser marking) on the surface23,24 or create special texture able to improve the substrate-coating interface.25,26 The aim of the research reported in this paper was to study the influence of different superficial laser treatment on the interface properties of cold-sprayed coating. Al–Si coating was produced by cold gas dynamic techniques on laser-treated AA 2024 T3 sheets, adopting a 30W Q-switched Yb:YAG fibre laser. Different roughness values and texture geometry were produced on the substrate by varying scanning strategy (i.e. the pattern adopted in the scansion) and keeping constant laser pulse power and scan speed.
Strength and failure behavior of carbon fiber reinforced aluminum laminates under flexural loading
Published in Mechanics of Advanced Materials and Structures, 2022
Rishi Kumar Gupta, Anirban Mahato, Anirban Bhattacharya
Surface roughness conditions obtained from 3D optical profilometer and surface topography obtained from FESEM of the aluminum sheets after surface modifications are shown in Figure 5. Anodizing of aluminum alloy was used as a surface pretreatment technique to alter the active surface with suitable surface morphology that can provide a porous oxide layer and increase surface energy. The surface of the aluminum sheet after solvent degreasing (MEK cleaning) is shown in Figure 5(a). This solvent degreasing removes the dirt particles from the surface of the aluminum sheet which prevents the formation of chemical bonds at the surface. The measured average roughness is 0.203 µm and the surface is free from any pores/cracks. It is clear from Figure 5(b) that after anodizing of aluminum surface some nonuniform pits in the form of nanopores are formed on the aluminum sheet surface. The presence of these pits enhances the adhesive strength between the sheet and prepreg by increasing the surface area and enhances mechanical interlocking by better infiltration of epoxy [13]. The roughness increases marginally to 0.305 µm after CAA treatment. The surface conditions of aluminum sheets obtained after surface modification by only 220 grit size abrasion, and mechanical abrasion by 220 grit followed by CAA treatment are shown in Figure 5(c,d). It is evident from Figure 5(c,d) that abrasion causes elongated ridges and pits on the aluminum sheet surface with reasonably high surface unevenness. The measured average surface roughness (Sa) values are about 1.92 µm and 1.52 µm for the aluminum surface modified by 220 size grit abrasion and 220 grit abrasion followed by CAA treatment, respectively. CAA treatment reduces the average surface roughness, however, nanopores and deep pits on the surface are created as can be seen in Figure 5(d). Nearly 3 to 5 times increase in surface roughness due to abrasion, enhances the surface area to make bonds and mechanical interlocking between the aluminum sheet and prepreg. However, with an increase in the surface area, there could be higher chances of air entrapment at interlayers that may lead to reduction in adhesion. Thus, the study of strength of the laminates formed with aluminum sheets under different treatment conditions could be utilized to optimize adhesion at the interface between the sheet and prepreg.