Investigation of mechanical properties of electroless nickel plated micro-lattice structures

Öz

In this study, mechanical properties of electroless nickel coated micro lattice structures were parametrically studied with both experimental and finite element methods. The micro lattice structures are produced of micro struts with a diameter of approximately 200 µm by selective laser melting (SLM) and are made of 316L stainless steel in the form of body centered cubic (BCC) structure. With electroless nickel coating method, a coating thickness of 17 µm was obtained and as a result, compression tests showed a 50% increase in specific elasticity modules and a 75% increase in specific strength for micro lattice structures. The effects of coating thickness and cell size on the mechanical performance of micro lattice structures were investigated by finite element method. Material parameters required for finite element method were obtained by using nano-indentation tests on the coating and inverse finite element algorithms. Studies showed that; The mechanical and failure properties of the coating material have a significant effect on improving the mechanical properties of the coated micro lattices. As a result, it was determined that, with higher the specific strength and ductility of the coating material, higher mechanical properties of the stainless-steel micro lattice structures can be achieved.

Anahtar Kelimeler

• Electroless Nickel Coating
• Selective Laser Melting
• Micro Lattice Structures
• Inverse Finite Element Analysis
• Nano-indentation

Akımsız nikel kaplanmış mikro kafes yapıların mekanik özelliklerinin incelenmesi

Öz

Bu çalışmada, akımsız nikel ile kaplanan mikro kafes yapıların mekanik özellikleri hem deneysel hem de sonlu elemanlar yöntemi kullanılarak parametrik olarak çalışılmıştır. Kullanılan mikro kafes yapılar seçici lazer ergitme (SLM) yöntemi ile yaklaşık 200µm çapında mikro tellerden oluşmakta olup, 316L paslanmaz çelik malzemeden hacim merkezli kübik (BCC) yapı şeklinde üretilmiştir. Uygulanan akımsız nikel kaplama yöntemi ile yaklaşık olarak 17 µm kaplama kalınlığı elde edilmiş ve bunun sonucunda gerçekleştirilen basma testleri sonucunda mikro kafes yapıların spesifik elastisite modüllerinde yaklaşık %50 ve spesifik mukavemetlerinde ise %75 artış elde edilmiştir. Kaplama kalınlığının ve hücre boyutu arasındaki ilişkilerin mikro kafes yapıların mekanik performansları üzerine etkileri sonlu elemanlar analizleri ile parametrik çalışmalar ile incelenmiştir. Sonlu elemanlar yönteminde malzeme modelleri için gerekli malzeme parametreleri kaplama için nano-indentasyon testler kullanılarak ve özgün olarak geliştirilen tersine sonlu elemanlar algoritması ile elde edilmiştir. Yapılan çalışmalar gösterdi ki; kaplama malzemesinin mekanik ve hasar özelliklerinin kaplanmış mikro kafeslerin mekanik özelliklerinin iyileştirilmesinde çok ciddi bir etkiye sahiptir. Sonuç olarak kaplama malzemesinin spesifik mukavemeti ve sünekliği ne kadar yüksek ise paslanmaz çelik mikro kafes yapıların spesifik mekanik özelliklerinin o derecede iyileşme göstereceği belirlenmiştir.

Anahtar Kelimeler

• Akımsız Nikel Kaplama
• Seçici Lazer Ergitme
• Mikro Kafes Yapılar
• Tersine Sonlu Elemanlar
• Nano-indentasyon

Kaynakça

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