What Do We Know, What are the Current Limitations of Suspension Plasma Spraying?

Fauchais, Pierre; Vardelle, Michel; Vardelle, Armelle; Goutier, Simon

doi:10.1007/s11666-015-0286-3

Cited by 88 publications

(39 citation statements)

References 58 publications

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“…In spite of this limitation suspensions with a solid loading significantly higher than those reported in previous works can be injected. It is an important achievement because, as explained above in the introduction section, an increase of the suspension solids content involves energy saving and consequently an easier industrial scaling [9,10,14,15].…”

Section: Suspension Preparationmentioning

confidence: 99%

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Alumina-zirconia coatings obtained by suspension plasma spraying from highly concentrated aqueous suspensions

Carpio

Salvador

Borrell

et al. 2016

Surface and Coatings Technology

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Suspension plasma spraying (SPS) deposition represents an innovative technique to produce coatings that exhibit improved properties. However, the key to obtain coatings with superior functional properties relies on the investigation of the suspensions as starting materials. For this reason, the present work deals with the suspension preparation for SPS process and its influence on the resulting coatings.Laboratory-prepared 60/40 wt% alumina-zirconia suspensions were concentrated to avoid energy loss and were then successfully deposited by SPS technique. The liquid used was water instead of ethanol due to economical, environmental and safety reasons. The preparation of the suspension plays an important role in SPS process since stable and well-dispersed water suspensions are difficult to obtain. For this reason, colloidal behaviour characterisation of the starting particles as well as rheological optimisation of the feedstock suspensions were addressed in this research.Suspensions with different solid loadings (up to 30 vol.% or 72 wt%) were deposited using several spraying distances. All coatings displayed a bimodal microstructure consisting in partially melted zones surrounded by a fully melted matrix. α-Al2O3 and t'-ZrO2 constituted the main crystalline phases, but differences in the microstructure and properties of the coatings were observed. From these results, some relations between starting suspension and spraying parameters with coating characteristics were found. Thus the optimal spraying distance becomes shorter when the suspension solid loading increases.

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Section: Suspension Preparationmentioning

confidence: 99%

“…Besides suspension viscosity cannot be too high for the suspension to properly flow through the injector. However it is interesting to note that solids loading of the suspension should be as high as possible so as to improve the deposition efficiency [9,10].…”

Section: Introductionmentioning

confidence: 99%

Alumina-zirconia coatings obtained by suspension plasma spraying from highly concentrated aqueous suspensions

Carpio

Salvador

Borrell

et al. 2016

Surface and Coatings Technology

View full text Add to dashboard Cite

show abstract

“…Hence, the coating build-up occurs in a different manner as compared to conventional APS spraying. Yet, thermal barrier coatings (TBCs) produced by SPS have already shown superior properties in terms of thermal properties and thermal shock resistance as compared to their APS counterparts (Ref 6,7). This is mainly due to the inter-columnar spacings which improve the strain tolerance of the coating and the presence of pores and micro-cracks which reduce the thermal conductivity (Ref 8).…”

Section: Introductionmentioning

confidence: 99%

3D Analysis of Porosity in a Ceramic Coating Using X-ray Microscopy

2017

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Suspension plasma spraying (SPS) is a new, innovative plasma spray technique using a feedstock consisting of fine powder particles suspended in a liquid. Using SPS, ceramic coatings with columnar microstructures have been produced which are used as topcoats in thermal barrier coatings. The microstructure contains a wide pore size range consisting of inter-columnar spacings, micro-pores and nano-pores. Hence, determination of total porosity and pore size distribution is a challenge. Here, x-ray microscopy (XRM) has been applied for describing the complex pore space of the coatings because of its capability to image the (local) porosity within the coating in 3D at a resolution down to 50 nm. The possibility to quantitatively segment the analyzed volume allows analysis of both open and closed porosity. For an yttria-stabilized zirconia coating with feathery microstructure, both open and closed porosity were determined and it could be revealed that 11% of the pore volumes (1.4% of the total volume) are closed pores. The analyzed volume was reconstructed to illustrate the distribution of open and closed pores in 3D. Moreover, pore widths and pore volumes were determined. The results on the complex pore space obtained by XRM are discussed in connection with other porosimetry techniques.

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“…SPS method is similar to APS with the difference that the material injected into the plasma torch is a suspension rather than a powdery material. One of the main advantages of SPS against APS process deals with the possibility of incorporating small particles (submicron-or even nanosized) through the liquid [5]. Although there are numerous research groups depositing coatings from suspensions of different types of ceramic materials, mainly oxides, only few groups have started to work with bioactive glass particles, so that this research line is still incipient [6,7].…”

Section: Introductionmentioning

confidence: 99%

Bioactive glass coatings by suspension plasma spraying from glycolether-based solvent feedstock

Cañas

Vicent

Orts

et al. 2017

Surface and Coatings Technology

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Bioactive glasses are emerging as a substitute of hydroxyapatite in the development of bioactive coatings for biomedical applications. The deposition of these coatings is carried out by a wide range of methods, being atmospheric plasma spraying the most employed technique. However, the research on the deposition of these coatings from suspension feedstocks by thermal spraying is still incipient, therefore more research about this topic is needed.Thus, a bioactive glass suspension, composed of fine glass particles, was prepared and stabilised through rheological and sedimentation tests to be used as a feedstock in plasma spraying. The solvent used in the suspension preparation was dipropylene glycol methyl ether in order to develop a new type of bioactive suspension. Consequently, as a new type of solvent was used, its effect on the plasma torch properties was determined. On other hand, the rheological behaviour of the suspension feedstock was assessed by means of a simple viscosity model. This suspension was deposited onto metallic substrates by plasma spraying, employing several spraying distances. All coatings displayed a suitable adherence and similar thickness.However, the microstructure of the obtained coatings is highly affected by the spraying distance as it can be seen in coatings surface and cross-section field emission gun environmental scanning electron microscopy examination. Thus, a relation between the spraying distance and coatings microstructure was found. On the other hand, X-ray diffraction confirmed the amorphous nature of the obtained coatings.

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What Do We Know, What are the Current Limitations of Suspension Plasma Spraying?

Cited by 88 publications

References 58 publications

Alumina-zirconia coatings obtained by suspension plasma spraying from highly concentrated aqueous suspensions

Alumina-zirconia coatings obtained by suspension plasma spraying from highly concentrated aqueous suspensions

3D Analysis of Porosity in a Ceramic Coating Using X-ray Microscopy

Bioactive glass coatings by suspension plasma spraying from glycolether-based solvent feedstock

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