Cold spray (CS) is a convenient and cost-effective alternative to standard repair and maintenance procedures. The uniqueness of CS rests in its potential to form a coating, provide structural repair, and even create a near-net-shaped part at temperatures far below the melting point of the feedstock powders, thus preventing or reducing several detrimental high-temperature reactions which are common in thermal spray processes. This nature of CS makes it appealing as a process for surface coatings or structural repair while preserving the material's unique properties. In this study, microstructural and mechanical characteristics of multiple alternative deposition strategies on stainless steel (SS) 316L coatings produced by a low pressure cold spray (LPCS) system are investigated. The difference of this study from other studies is the usage of the LPCS system to spray high strength material with low pressure and low temperature rather than common high pressure cold spray (HPCS) systems. The first study addresses to investigate the performance of a novel LPCS device by characterizing CS coatings deposited with different combinations of spraying parameters; gas pressure, gas temperature, traverse gun speed, and powder feed rate. While the second study aims to investigate the effect of spray gun feed-powder injection angle on the characterization of SS 316L CS coatings deposited with a commercial LPCS device. In the first study, the results demonstrated that high gas pressure and high gas temperature play a major role in producing well-bonded and dense coatings while traverse gun speed and powder feed rate have an effect on the coatings’ thickness and profile shape. The results of the second study showed that deposition strategy must be designed with 0° or 180° spray gun feed-powder injection angle for addressing the optimal deposition quality in terms of symmetrical and uniform coating profiles.
Cold spray (CS) è un'alternativa conveniente ed economica alle procedure di riparazione e manutenzione standard. L'unicità del CS risiede nella sua capacità di formare un rivestimento, fornire riparazione strutturale e persino creare una parte di forma semifinita a temperature molto al di sotto del punto di fusione delle polveri di materia prima, prevenendo o riducendo così diverse reazioni dannose ad alta temperatura che sono comuni nei processi di spruzzatura termica. La natura del CS lo rende interessante come processo per rivestimenti superficiali o riparazione strutturali, preservando le proprietà uniche del materiale. In questo studio, vengono esaminate le caratteristiche microstrutturali e meccaniche di molteplici strategie di deposizione alternative su rivestimenti in acciaio inossidabile 316L, prodotti da un sistema LPCS (Low Pressure Cold Spray). La differenza di questo studio rispetto ad altri studi è l'utilizzo del sistema LPCS per spruzzare materiale ad alta resistenza a bassa pressione e bassa temperatura piuttosto che con i comuni sistemi HPCS (High Pressure Cold Spray). Il primo studio si propone di indagare le prestazioni di un nuovo dispositivo LPCS caratterizzando i rivestimenti CS depositati con diverse combinazioni di parametri di spruzzatura: pressione del gas, temperatura del gas, velocità della pistola e velocità di alimentazione della polvere. Mentre il secondo studio mira ad indagare l'effetto dell'angolo di spruzzatura iniezione polvere-alimentazione pistola sulla caratterizzazione dei rivestimenti SS 316L CS depositati con un dispositivo LPCS commerciale. Nel primo studio, i risultati hanno dimostrato che l'alta pressione del gas e l'alta temperatura del gas svolgono un ruolo importante nella produzione di rivestimenti ben aderenti e densi, mentre la velocità della pistola e la velocità di alimentazione della polvere hanno un effetto sullo spessore e sulla forma del profilo dei rivestimenti. I risultati del secondo studio hanno mostrato che la strategia di deposizione deve essere progettata con un angolo di 0 ° o 180 ° per affrontare la qualità di deposizione ottimale in termini di profili di rivestimento simmetrici e uniformi.
Different deposition strategies to enhance microstructural and mechanical properties of cold-spray applications
Aykut, Cansu
2019/2020
Abstract
Cold spray (CS) is a convenient and cost-effective alternative to standard repair and maintenance procedures. The uniqueness of CS rests in its potential to form a coating, provide structural repair, and even create a near-net-shaped part at temperatures far below the melting point of the feedstock powders, thus preventing or reducing several detrimental high-temperature reactions which are common in thermal spray processes. This nature of CS makes it appealing as a process for surface coatings or structural repair while preserving the material's unique properties. In this study, microstructural and mechanical characteristics of multiple alternative deposition strategies on stainless steel (SS) 316L coatings produced by a low pressure cold spray (LPCS) system are investigated. The difference of this study from other studies is the usage of the LPCS system to spray high strength material with low pressure and low temperature rather than common high pressure cold spray (HPCS) systems. The first study addresses to investigate the performance of a novel LPCS device by characterizing CS coatings deposited with different combinations of spraying parameters; gas pressure, gas temperature, traverse gun speed, and powder feed rate. While the second study aims to investigate the effect of spray gun feed-powder injection angle on the characterization of SS 316L CS coatings deposited with a commercial LPCS device. In the first study, the results demonstrated that high gas pressure and high gas temperature play a major role in producing well-bonded and dense coatings while traverse gun speed and powder feed rate have an effect on the coatings’ thickness and profile shape. The results of the second study showed that deposition strategy must be designed with 0° or 180° spray gun feed-powder injection angle for addressing the optimal deposition quality in terms of symmetrical and uniform coating profiles.| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/175333