scholarly journals Design of Magnesia–Spinel Bricks for Improved Coating Adherence in Cement Rotary Kilns

Ceramics ◽  
2021 ◽  
Vol 4 (4) ◽  
pp. 652-666
Author(s):  
Graziella Rajão Cota Pacheco ◽  
Geraldo Eduardo Gonçalves ◽  
Vanessa de Freitas Cunha Lins
Keyword(s):  
Formation Mechanism ◽  
Firing Temperature ◽  
Essential Role ◽  
Refractory Lining ◽  
Refractory Structure ◽  
Prolonged Operation ◽  
Magnesia Spinel ◽  
Coating Formation ◽  
Rotary Kilns ◽  
Coating Formation Mechanism

It is well known that doloma bricks present better coating adherence than magnesia–spinel bricks when applied in cement rotary kilns, which is related to the different coating formation mechanism. The coating has an essential role in prolonged operation by protecting the refractory lining; thus, it is important to improve its adherence on magnesia–spinel refractories. The objective of this investigation is to study different compositions of magnesia–spinel bricks, achieved by varying additives used (calcined alumina, limestone, hematite and zirconia) and firing temperature (1500 °C and 1700 °C), to enhance the coating adherence measured by the sandwich test. The results have pointed out that the use of higher firing temperature contributes positively to physical adherence due to well-sintered refractory structure and elevated permeability, attaining coating strength superior to 2 MPa. For the chemical adherence, the addition of 2 wt.% of limestone increased the coating strength to 3 MPa, but resulted in a drop in hot properties. In this context, the most suitable approach to improve adherence of clinker coating and maintain hot properties in suitable levels is to increase the firing temperature.

Adhesion Phenomenon of Titanium as Cathode in Aluminum Anodizing

2015 ◽  
Vol 799-800 ◽  
pp. 140-144 ◽  
Author(s):  
Putu Hadi Setyarini ◽  
Rudy Soenoko ◽  
Agus Suprapto ◽  
Yudy Surya Irawan
Keyword(s):  
Formation Mechanism ◽  
Electric Potential ◽  
Film Coating ◽  
Titanium Content ◽  
Deposition Surface ◽  
Coating Formation ◽  
Coating Formation Mechanism ◽  
Aluminum Anodizing

This paper discusses the film coating formation mechanism after an anodizing process carried out in AA6061 with a varying potential between 15-30V. The electrolyte used to be 1M H3PO4with titanium as the cathode. From this study, it was found that after the anodizing process the pore uniformity occurs with a size varied from 1.09-5.74 μm become 2.78-4.56 μm. There was also an increase in the titanium content on the deposition surface about 21% and was achieved at an electric potential of 25V where titanium in the pore penetration occurs up to the depth of 5 μm.

The kiln coating formation mechanism of MgO–FeAl2O4 brick

2016 ◽  
Vol 42 (1) ◽  
pp. 569-575 ◽  
Author(s):  
Junhong Chen ◽  
Mingwei Yan ◽  
Jindong Su ◽  
Bin Li ◽  
Jialin Sun
Keyword(s):  
Formation Mechanism ◽  
Coating Formation ◽  
Coating Formation Mechanism

scholarly journals Characterising Mass-resolved Mixing State of Black Carbon in Beijing Using a Morphology-Independent Measurement Method

2019 ◽  
Author(s):  
Chenjie Yu ◽  
Dantong Liu ◽  
Kurtis Broda ◽  
Rutambhara Joshi ◽  
Jason Olfert ◽  
...  
Keyword(s):  
Black Carbon ◽  
Formation Mechanism ◽  
Coating Thickness ◽  
Process Models ◽  
Urban Site ◽  
Pollution Level ◽  
Inversion Method ◽  
Mixing State ◽  
Coating Formation ◽  
Coating Formation Mechanism

Abstract. Refractory Black Carbon (rBC) in the atmosphere is known for its significant impact on the climate system in the atmosphere. The relationship between the microphysical and optical properties of rBC remain uncertain and are largely influenced by the size, coating thickness and mixing state of particles. This study presents a coupling of a centrifugal particle mass analyser (CPMA) and a single particle soot photometer (SP2) for the morphology-independent quantification of the mixing state of rBC-containing particles, used in the urban site of Beijing as part of the Air Pollution and Human Health-Beijing (APHH-Beijing) project during winter (10th Nov–10th Dec) and summer (18th May–25th June). An inversion method is applied to the measurements to present a two-variable distribution of both rBC core mass and total mass of rBC-containing particles and present the mass-resolved mixing state of rBC-containing particles. The mass ratio between non-rBC coating and rBC core (MR) is calculated to determine the coating thickness of the rBC-containing particles. The bulk MR was found to vary between 2–12 in winter and between 2–3 in summer. This mass-resolved mixing state is used to derive the mixing state index (χ) for the rBC-containing particles. χ quantifies whether the coating is evenly distributed across the rBC-containing particle population and is used to determine the degree of internal and external mixture of rBC-containing particles. The rBC-containing particles in Beijing were found to be 55%–70 % internally mixed in winter depending on the dominant air masses. χ of rBC-containing particles was highly positively associated with increased bulk MR, rBC mass loading or pollution level in winter, whereas χ of rBC-containing particles in summer varied significantly (ranging 60 %–75 %) within the narrowly-distributed bulk MR and was found to be independent of air mass sources. This concludes that the bulk MR may only act as a predictor of mixing state in winter, and χ is better to quantify the mixing state of rBC-containing particles. The same level of bulk MR corresponded with a higher χ in summer than in winter and this tended to suggest a limited formation of coatings on rBC largely depended on primary sources. However, with the higher Non-refractory PM1 (NR-PM1) concentration in winter, the coagulation process may still lead relative thick coatings. In summer the higher secondary compounds made the rBC-containing particles more homogeneous. But due to the higher temperatures and limited pollution level, the coating thickness in summer is limited. The mixing state of rBC-containing particles should also depend on the coating formation mechanism, both primary source influence and secondary coating formation mechanism should be considered in interpreting the rBC-containing particles mixing state in the atmosphere. This particle morphology-independent and mass-based data format as introduced in this study could be conviently applied in particle-resolved or other process models to investigate atmospheric rBC aging and mixing state properties.

scholarly journals Mechanical coating formed under conditions of vibration exposure

2020 ◽  
Vol 175 ◽  
pp. 05023 ◽  
Author(s):  
Vladimir Ivanov ◽  
Sergey Popov ◽  
Nikolai Dontsov ◽  
Galina Ekinil ◽  
Julia Oleynikova ◽  
...  
Keyword(s):  
Formation Mechanism ◽  
Mechanochemical Synthesis ◽  
Zinc Coating ◽  
Low Frequency ◽  
Vibration Exposure ◽  
Study Results ◽  
Coating Formation ◽  
Zinc Coatings ◽  
Coating Formation Mechanism ◽  
Mechanical Coating

The study results of the zinc coating obtained on the surface of metals in the process of mechanochemical synthesis, implemented in the conditions of vibrowave systems, are presented. The features of coating formation mechanism, an activating role in its formation of free-moving, under the influence of low-frequency vibrations, indenters, are disclosed. The advantages of applying zinc coatings method in comparison with traditional methods are shown.

Wire-feed deposition TiB reinforced Ti composite coating: Formation mechanism and tribological properties

2018 ◽  
Vol 229 ◽  
pp. 221-224 ◽  
Author(s):  
Yang Bao ◽  
Lujun Huang ◽  
Qi An ◽  
Shan Jiang ◽  
Lin Geng ◽  
...  
Keyword(s):  
Composite Coating ◽  
Formation Mechanism ◽  
Tribological Properties ◽  
Coating Formation ◽  
Coating Formation Mechanism ◽  
Wire Feed

The radioactive tracer method of studying the erosion of the refractory lining in the sintering zone of rotary kilns

Refractories ◽  
1977 ◽  
Vol 18 (3-4) ◽  
pp. 223-226
Author(s):  
V. I. Shubin ◽  
V. I. Nikonorov ◽  
Yu. A. Kurbatov ◽  
O. M. Stanulionis ◽  
V. P. Vasil'ev ◽  
...  
Keyword(s):  
Refractory Lining ◽  
Radioactive Tracer ◽  
Tracer Method ◽  
Rotary Kilns ◽  
Radioactive Tracer Method

scholarly journals Qualitative and Quantitative Coating Tests: A Comparison in Magnesia–Spinel Refractory Bricks

Ceramics ◽  
2020 ◽  
Vol 3 (1) ◽  
pp. 144-154 ◽  
Author(s):  
Graziella Pacheco ◽  
Geraldo Eduardo Gonçalves ◽  
Vanessa Lins
Keyword(s):  
Thermomechanical Properties ◽  
Contact Method ◽  
Test Results ◽  
Protection Mechanism ◽  
Subjective Analysis ◽  
Qualitative And Quantitative ◽  
Magnesia Spinel ◽  
Rotary Kilns ◽  
Refractory Bricks ◽  
Adherence Ability

In cement processing, which involves the production of clinker in rotary kilns, the main refractories used in the transition and burning zones are magnesia–spinel bricks. These bricks present suitable chemical and thermomechanical properties, not to mention that they can be easily landfilled. Among the main wear mechanisms of these bricks in the kiln, the infiltration of alkaline salts is noteworthy and occurs through the open pores of the refractory. In this way, the coating—a clinker layer adhered to the brick surface—appears as a protection mechanism of the lining against infiltration. Thus, the objective of this investigation is to run a qualitative coating test based on the contact method, and quantitative coating test based on the sandwich method to check the suitability of the methodologies and to evaluate the coating adherence on two different magnesia–spinel bricks. It was possible to distinguish the superior adherence ability of brick B in both coatings due to the higher porosity and the presence of nonreacted ZrO2. Despite the similarity between the test results, the quantitative sandwich-coating test is preferable because it does not depend on subjective analysis.

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