This study compares pure Ni coatings deposited on type 316H stainless steel using high-velocity oxy-fuel (HVOF) and directed energy deposition (DED) processes. Microstructural analysis showed that DED produced more uniform claddings with fewer pores, while HVOF resulted in incomplete melting and cracks. Elemental diffusion of Cr and Fe from the substrate into the cladding was evident in DED samples, especially at higher laser power, but minimal in HVOF due to low heat input. Vickers hardness testing revealed that DED claddings had higher hardness near the interface, which was attributed to solid solution strengthening and reduced porosity. Although HVOF better suppressed diffusion, it exhibited inferior mechanical properties due to internal defects. Overall, the DED process demonstrated superior coating quality and mechanical performance, suggesting its suitability for corrosion-resistant applications requiring both structural integrity and thermal stability, such as molten salt reactors.

1. Introduction 
2. Experimental Section 
3. Results and Discussion 
    3.1 클래딩 후 시편 표면 특성 
    3.2 미세조직 분석 및 공정비교 
    3.3 클래딩 경계부에서의 미소경도특성 
4. Conclusion 
Funding
Conflict of Interest 
Data Availability Statement 
Author Information and Contribution 
Acknowledgments
References

• 이원찬(국립한밭대학교 신소재공학과) | Won Chan Lee (Department of Materials Science & Engineering, Hanbat National University, Daejeon 34158, Republic of Korea)
• 남승주(국립한밭대학교 신소재공학과) | Seung Ju Nam (Department of Materials Science & Engineering, Hanbat National University, Daejeon 34158, Republic of Korea)
• 김정한(국립한밭대학교 신소재공학과) | Jeoung Han Kim (Department of Materials Science & Engineering, Hanbat National University, Daejeon 34158, Republic of Korea) Corresponding author
• 윤지현(한국원자력연구원 재료안전기술연구부) | Ji-Hyun Yoon (Department of Nuclear Materials Safety Research Division, Korea Atomic Energy Research Institute, Daejeon 34057, Republic of Korea)