PENGARUH PERLAKUAN VARIASI ALMEN PADA SHOT PEENING DAN ELECTROPLATING Ni-Cr PADA AISI 304 TERHADAP LAJU KOROSI DALAM LARUTAN SYNTHETIC BODY FLUID (SBF) DAN LAJU PERAMBATAN RETAK FATIK

SAMBODO ARIF WIBOWO, Priyo Triiswanto, ST., M.Eng., Ph.D.Eng.

2015 | Tesis | S2 Teknik Mesin

Plat penyambung tulang merupakan alat bantu yang sangat penting bagi pasien patah tulang, yang berfungsi untuk menggantikan menahan beban tubuh selama proses perawatan dan penyembuhan. Banyaknya kasus kegagalan yang prematur pada struktur plat penyambung baik produk lokal maupaun impor, mahalnya produk impor, banyaknya produk impor yang masuk Indonesia, menjadi pelecut semangat persatuan para peneliti, perekayasa, akademisi, mahasiswa teknik mesin, teknik metallurgi, kedokteran untuk melakukan kajian dan riset bagaimana mekanisme kegagalannya dan bagaimana solusinya serta dalam rangka menghadapi Masyarakat Ekonomi Asean (MEA) 2015 ini. Dari hasil kajian yang berbentuk buku, jurnal nasional maupun international, seminar menunjukan bahwa retak fatik dan korosi adalah penyebab utama kegagalan struktur plat penyambung tulang dimana kebanyakan materialnya adalah AISI 304. Dengan penerapan shot peenig dan electroplating Ni-Cr diharapkan memperlambat perambatan retak fatik dan menurunkan laju korosinya, sehingga kegagalan yang prematur bisa dihindari. Shot peening merupakan salah satu metode yang bisa meningkatkan umur fatigue material, yaitu dengan penembakan bola baja berkecepatan tinggi dan terkendali ke permukaan material AISI 304 yang menyebabkan terinduksinya tegangan tekan di permukaan, membentuk lapisan deformasi plastis yang tipis, kekerasan meningkat, porositas menurun. Hal inilah yang menyebabkan inisiasi perambatan retak fatik meningkat (lama) sehingga laju perambatan retak fatik melambat. Sedangkan pelapisan electroplating Ni-Cr yaitu pelapisan yang berdasarkan proses elektrolisis dengan menggunakan ion-ion logam Ni dan Cr melalui larutan elektrolit chloride sulfate dan chromic acid yang diberi arus listrik DC, sehingga ion-ion logam Ni-Cr terurai dan menempel/mengendap di spesimen. Dengan pelapisan electroplating Ni-Cr selama 5 menit untuk masing – masing dan menvariasikan almen pada shot peening yaitu A0.003, A0.004, A0.006, A0.008, A0.010. Diharapkan lapisan yang terbentuk bisa diketahui karakteristik setiap perlakuan yang memperlambat laju korosi dalam larutan synthetic body fluid (SBF) dan memperlambat laju perambatan retak fatik sesuai spesifikasi standard untuk material biomedis plat penyambung tulang. Hasil penelitian laju korosi dalam larutan synthetic body fluid (SBF), yaitu spesimen A0.010 sebesar 0,0047 mpy, spesimen A0.008 sebesar 0,016 mpy, spesimen A0.006 sebesar 0,0192 mpy, spesimen A0.004 sebesar 0,0232 mpy, Spesimen A0.003 sebesar 0,0337 mpy. Hasil uji kekerasan mikro Vickers logam dasar yaitu 160 kg/mm2, Spesimen A0.008+Ni-Cr sebesar 345,945 kg/mm2, spesimen A0.010+Ni-Cr sebesar 335,717 kg/mm2, spesimen A0.006+Ni-Cr sebesar 305,123 kg/mm2, Spesimen A0.004+Ni-Cr sebesar 300 kg/mm2, Spesimen A0.003+Ni- Cr sebesar 297 kg/mm2. Sementara hasil uji perambatan retak fatik spesimen A0.006 dengan konstanta Paris C = 2x10-11 dan n = 3,64, Spesimen A0.008 dengan C = 5x10-14 dan n = 6,23, spesimen A0.010 dengan C = 9x10-13 dan n = 3,45, dan spesimen tanpa permukaan dengan C = 5x10-11 dan n = 3,45.

Connector plate of bone is a very important devicess for patients bone fracture, which serves to replace the weight of the body during the treatment and healing. The number of cases of premature failure at connector plate structure both local and imported products, the high cost of imported products, the number of products imported into Indonesia, became a spirit of unity motivation for researchers, engineers, academicians, students of mechanical engineering, metallurgy engineering, medicine to conduct studies and research how the failure mechanism and how the solution and in order to face the ASEAN Economic Community (AEC) 2015. From the results of the study in the form of books, national and international journals, conference showed that the fatigue cracks and corrosion is a major cause of failure of the bone connecting plate structure in which most of the material is AISI 304. With the implementation shot peening and electroplating Ni-Cr expected to slow the fatigue crack growth rate and decrease corrosion rate, so that premature failure can be avoided. Shot peening is one of method that can be improve the fatigue life of materials, namely steel ball with high-speed shooting and restrained, to the surface of AISI 304 material that causes the induced compressive stress on the surface, forming a thin layer of plastic deformation, increased hardness, porosity decreases. This has led to the initiation of fatigue crack growth propagation increased (long) so as to slow down the rate of fatigue crack growth propagation. While electroplating Ni-Cr coating is a coating that is based on the electrolysis process using metal ions Ni and Cr, through the electrolyte chromic acid solution and chloride sulfate solution were given a DC electric current, so that the metal ions Ni-Cr decompose and deposition in specimens. With electroplating Ni-Cr coating for 5 minutes for each other and varies the shot peening is Almen on A0.003, A0.004, A0.006, A0.008, A0.010. Expected layer formed can be known characteristics of each treatment that slows the rate of corrosion in a solution of synthetic body fluid (SBF) and slow the rate of fatigue crack propagation appropriate standard specifications for connecting bone plate biomedical materials. The results of the corrosion rate studies in the solution of synthetic body fluid (SBF), which A0.010 specimen amount of 0.0047 mpy, A0.008 specimens amount of 0.016 mpy, A0.006 specimen amount of 0.0192 mpy, A0.004 specimen A0.004 amount of 0.0232 mpy, A0.003 specimen amount of 0.0337 mpy. The results of micro Vickers hardness test on the base metal is 160 kg / mm2, A0.008 + Ni-Cr specimen amounted of 345.945 kg / mm2, A0.010 + Ni-Cr specimen amounted of 335.717 kg / mm2, A0.006 + Ni-Cr specimen amount of 305.123 kg / mm2, A0.004 + Ni-Cr specimen of 300 kg / mm2, A0.003 + Ni-Cr specimen amounted of 297 kg / mm2. While the results of fatigue crack propagation test of A0.006 specimens with Paris Constant C= 2x10-11 and n= 3.64, A0.008 specimen with C= 5x10-14 and n= 6.23, A0.010 specimens with C= 9x10-13 and n= 3.45, and the non-treatment specimen with the C= 5x10-11 and n= 3.45

Kata Kunci : AISI 304, Larutan SBF, Shot Peening, Electroplating Ni-Cr, Korosi, Perambatan Retak Fatik, Konstanta Paris