Surface quality and microstructure of low-vacuum sintered orthodontic bracket 17-4 PH stainless steel fabricated by MIM process

Bambang Suharno, Lingga Pradinda Suharno, Hantoro Restucondro Saputro, Bambang Irawan, Tjokro Prasetyadi, Deni Ferdian, Sugeng Supriadi

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

2 Citations (Scopus)

Abstract

Surface roughness and microstructure play important role on orthodontic bracket quality. Therefore, orthodontic brackets need to have smooth surface roughness to reduce the friction and bacterial adhesion. Microstructure of orthodontic brackets also determine the mechanical properties and corrosion resistance. There are two methods to produce orthodontic bracket, investment casting and metal injection molding. The purpose of this study is to observe the surface roughness and microstructure of orthodontic bracket which were made from two different fabrication methods. To produce orthodontic bracket with metal injection molding method, 17-4 PH stainless steel feedstock was injected to the orthodontic bracket mold using injection molding machine. After injection, the binder was eliminated with solvent and thermal debinding. Solvent debinding process was conducted with hexane at 50 °C on magnetic stirrer for 1.5 hours. Thermal debinding process was conducted at 510°C with 0.5°C/min heat rate and 120 min holding time. Hereafter, sintering process were performed with vacuum tube furnace at 1360°C with heat rate 5°C/min and 90 min holding time in low vacuum atmosphere. To produce orthodontic bracket with investment casting method, the wax was injected into the mold then the wax pattern was arranged into the tree form. The tree form was then dipped into ceramic slurry and allowed to harden, the ceramic slurry has a thickness in the region of 10 mm. The ceramic mold was then heated at a temperature of over than 1100°C to strengthen the ceramic mold and to remove the remaining wax. After that, the molten 17-4 PH stainless steel was poured into the ceramic mold at a temperature of over 1600°C. The natural cooling process was carried out at temperature of 25°C, after which the ceramic mold was broken away. Then, the orthodontic bracket was cut from the tree form. The results show that the orthodontic bracket which were made with investment casting fabrication method have low porosity, high density, and there is no indication of secondary phase on the microstructure. However, it has rough brackets surface. Whereas, the production of orthodontic brackets using metal injection molding method resulted in better surface roughness. But, it has relatively high porosity, presence of another phase on the microstructure, and low density.

Original languageEnglish
Title of host publication2nd Biomedical Engineering�s Recent Progress in Biomaterials, Drugs Development, and Medical Devices
Subtitle of host publicationProceedings of the International Symposium of Biomedical Engineering, ISBE 2017
EditorsRadon Dhelika, Yudan Whulanza, Ghiska Ramahdita, Praswasti P.D.K. Wulan
PublisherAmerican Institute of Physics Inc.
ISBN (Electronic)9780735416253
DOIs
Publication statusPublished - 13 Feb 2018
Event2nd Biomedical Engineering's Recent Progress in Biomaterials, Drugs Development, and Medical Devices, ISBE 2017 - Bali, Indonesia
Duration: 25 Jul 201726 Jul 2017

Publication series

NameAIP Conference Proceedings
Volume1933
ISSN (Print)0094-243X
ISSN (Electronic)1551-7616

Conference

Conference2nd Biomedical Engineering's Recent Progress in Biomaterials, Drugs Development, and Medical Devices, ISBE 2017
Country/TerritoryIndonesia
CityBali
Period25/07/1726/07/17

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