A new electrochemical method for the determination of the free surface of phosphate layers

Losch, Anchor R.; Schultze, J.W.; Speckmann, H.‐D.

doi:10.1016/0169-4332(91)90111-v

Cited by 30 publications

(5 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As the name suggests, it combines a spray process that quickly transports ions to readily accessible surfaces by means of mostly momentum and a dip processes that transports ions to complex hidden surfaces by means of mostly diffusion. Also relevant to automotive bodies was work by Losch et al on measuring phosphate coating porosity by electrochemical means [27]. The uncoated surface area in the pores acts as an adhesion interface for ED (electrodeposition) and as a measure of coating coverage.…”

Section: Conversion Coatingsmentioning

confidence: 99%

Advances in Automotive Conversion Coatings during Pretreatment of the Body Structure: A Review

et al. 2018

View full text Add to dashboard Cite

Automotive conversion coatings consist of layers of materials that are chemically applied to the body structures of vehicles before painting to improve corrosion protection and paint adhesion. These coatings are a consequence of surface-based chemical reactions and are sandwiched between paint layers and the base metal; the chemical reactions involved distinctly classify conversion coatings from other coating technologies. Although the tri-cationic conversion coating bath chemistry that was developed around the end of the 20th century remains persistent, environmental, health, and cost issues favor a new generation of greener methods and materials such as zirconium. Environmental forces driving lightweight material selection during automobile body design are possibly more influential for transitioning to zirconium than the concerns regarding the body coating process. The chemistry involved in some conversion coatings processing has been known for over 100 years. However, recent advances in chemical processing, changes in the components used for vehicle body structures, environmental considerations and costs have prompted the automobile industry to embrace new conversion coatings technologies. These are discussed herein along with a historical perspective that has led to the use of current conversion coatings technologies. In addition, future directions for automobile body conversion coatings are discussed that may affect conversion coatings in the age of multi-material body structures.

show abstract

Section: Conversion Coatingsmentioning

confidence: 99%

Advances in Automotive Conversion Coatings during Pretreatment of the Body Structure: A Review

et al. 2018

View full text Add to dashboard Cite

show abstract

“…This technique presented serious limitations for thin coating analyses, since the effect of the resistance inside pores became less significant 4 . Typical porosity tests for phosphate coating analyses are the ferrocyanide test and the copper deposition test; however, electrochemical tests ensure better control of the test conditions 11 . Weng et al studied the porosity of zinc and manganese phosphate coatings 12 , using the polarization resistance technique and obtaining an average porosity of less than 1.5% for zinc and manganese coatings 12 .…”

Section: Introductionmentioning

confidence: 99%

“…Weng et al studied the porosity of zinc and manganese phosphate coatings 12 , using the polarization resistance technique and obtaining an average porosity of less than 1.5% for zinc and manganese coatings 12 . In this work, the electrochemical Voltammetric Anodic Dissolution (VAD) technique 11,13 , in which the passivation charge of the substrate is measured, is used to determine the phosphate coating porosity of galvanized steel (GS) foils prepared under different phosphatization conditions. The advantages of this technique are the short analysis time (about 1 min) and the fact that a calibration curve is unnecessary, requiring only the passivation standard charge (substrate with unitary porosity without coating).…”

Section: Introductionmentioning

confidence: 99%

Analysis of Electrochemical Porosity of Phosphatized Coatings on Galvanized Steel Substrate

Ponte

Maul

Alvarenga³

2002

Mat. Res.

View full text Add to dashboard Cite

This work refers to the application of a Voltammetric Anodic Dissolution (VAD) Technique in the analysis of coating discontinuities, focusing on pores and cracks that exposed the substrate. An evaluation was made of the influence of several parameters, such as the concentration of the passivation solution and sweep rate (SR), on the substrate passivation process and on the porosity indexes of tricationic phosphate coatings of Fe/Zn/Mn. The phosphatization process used was a commercial tricationic Fe/Zn/Mn phosphate bath applied on a galvanized steel (GS) substrate. Once the best experimental conditions for the use of the VAD technique had been defined, the grain size and layer weight were related to porosity indexes. The porosity was found to show a tendency to decrease with increasing grain size. The VAD technique consists of the anodic polarization of the substrate/coating system and measurement of the charge density involved in the substrate passivation process. A quantitative porosity index was obtained by comparing the passivation charge density of the substrate without coating (standard passivation charge density) and the passivation charge of the coated substrate.

show abstract

“…Losch et al established a method to determine the coverage of phosphate layers with CV measurements . This method was already used to analyze the coverage of different types of layers on a variety of substrates like zinc-coated steel. ,, Similar to this method, the coverage of ZM-coated steel samples by the LDH conversion layer was calculated.…”

Section: Methodsmentioning

confidence: 99%

Environmentally Friendly Layered Double Hydroxide Conversion Layers: Formation Kinetics on Zn–Al–Mg-Coated Steel

Holzner

Luckeneder

Strauß

et al. 2022

ACS Appl. Mater. Interfaces

View full text Add to dashboard Cite

Phosphate- or chromate-based industrially produced conversion layers, while effectively increasing adhesion for organic coatings and corrosion resistance, come at the cost of environmentally problematic and harmful treatment solutions and waste. In this respect, layered double hydroxide (LDH)-based conversion layers offer an environmentally benign alternative without toxicologically concerning compounds in the treatment solution. Here, we study an LDH conversion layer on Zn–Al–Mg-coated steel (ZM-coated steel), which was produced by immersion into a carbonate- and magnesium-containing alkaline solution. The mechanism and kinetics of the conversion layer formation were investigated with in situ open circuit potential measurements, cyclic voltammetry (CV), and scanning electron microscopy (SEM). Acceleration of the LDH layer formation through high convection in the treatment solution was found. This was attributed to a higher oxygen availability at the metal/solution interface because no diffusion-limited state during the layer formation is reached due to high convection. The importance of oxygen within the kinetics indicates a corrosion-like mechanism, with cathodic and anodic sites on the steel sample. The LDH formation happens by co-precipitation of ions present in the treatment solution and dissolved ions from the ZM-coated steel. With CV, SEM, and X-ray diffraction, the growth of the LDH conversion layer was investigated with respect to the immersion time. It was found that after 30 s, the sample surface was almost fully covered with an LDH layer, and with the increasing immersion time, the layer grows in thickness. Increased understanding on the kinetics and mechanism of the LDH conversion layer formation on ZM-coated steel gives rise to a targeted optimization of the treatment solution and process parameters.

show abstract

A new electrochemical method for the determination of the free surface of phosphate layers

Cited by 30 publications

References 9 publications

Advances in Automotive Conversion Coatings during Pretreatment of the Body Structure: A Review

Advances in Automotive Conversion Coatings during Pretreatment of the Body Structure: A Review

Analysis of Electrochemical Porosity of Phosphatized Coatings on Galvanized Steel Substrate

Environmentally Friendly Layered Double Hydroxide Conversion Layers: Formation Kinetics on Zn–Al–Mg-Coated Steel

Contact Info

Product

Resources

About