Perlakuan Panas Komposit berbasis Aluminium/ Zirconium Hasil Equal Channel Angular Pressing (ECAP) - Paralel Channel

AbstrakProses produksi dengan menggunakan metode pengerjaan logam konvensional seringkali sulit terutama untuk produk masif, dimana peralatan dan produk seperti gaya dan tekanan tinggi diperlukan. Keterbatasan ini bisa diatasi dengan menggunakan teknologi terbaru yaitu severe plastic deformation (SPD), dengan metode spesifiknya yaitu equal channel angulatr pressing (ECAP). Perkembangan ECAP sudah mencapai tahap aplikasi produk, salah satu pengembangan metodenya yaitu model parallel channel, atau disebut ECAP-PC. Dalam aplikasi pembuatan komponen, diperlukan proses perlakuan panas material, bertujuan untuk mengubah sifat material. Perlakuan panas yang sesuai diantaranya adalah proses pelunakan anealling untuk pengerjaan komponen dan perlakuan panas jenis T6; artificial aging/age-hardening sebagai proses akhir, untuk penerapan aplikasi tertentu. Serbuk aluminium (Al) dengan campuran zirconium (Zr) diaktivasi secara mekanis menggunakan ball milling. Pencampuran menggunakan cairan etanol dan heptane untuk memudahkan pengeringan. Fraksi volume yang digunakan dalam komposit Al sebagai matriks dan Zr yaitu 97:3%. Serbuk komposit dilakukan penggilingan dengan proses ball milling menggunakan putaran 60 rpm selama 24 jam. Hasil perlakuan panas age-hardening menghasilkan sifat mekanik tertinggi sebesar 144-222 HV/1406-2177 MPa dibanding dengan jenis annealing yaitu 31-46 HV/301-449 MPa. Hal ini sesuai dengan tujuan dari perlakuan panas yaitu untuk menurunkan sifat mekanik agar material mudah diproses. AbstractThe production of conventional metalworking methods is often difficult especially for massive products, where equipment and products such as high force and pressure are required. This limitation can be overcome by using the latest technology, namely severe plastic deformation (SPD). By specific method, namely Equal Channel Angular Pressing (ECAP). The development of ECAP has reached the product application stage, one of the methods development is parallel channel model, or called ECAP-PC. Application of component manufacturing requires a material heat treatment process, aims to change the properties of the material. Suitable heat treatments include the annealing softening process for component work and the T6 type heat treatment; artificial aging/age-hardening as a finishing process for the application of certain applications. Aluminum (Al) powder and zirconium (Zr), mixture were activated mechanically by ball milling. Mixing processed using liquid ethanol and heptane for easy drying. The volume fraction used in the Al composite as a matrix and Zr is 97: 3%. The composites powder was milled by ball milling used a 60 rpm rotation for 24 hours. The results of age-hardening heat treatment produced the highest mechanical properties of 144-222 HV / 1406-2177 MPa compared to the type of annealing, namely 31-46 HV / 301-449 MPa. This is in accordance with the purpose of heat treatment, namely to reduce mechanical properties so that the material is easy to process.

The Basic Thermal Hydraulic Issues of Applying Supercritical Fluid to Nuclear Reactors

This chapter is mainly focused on illustrating some introductory progress on thermal hydraulic issues of supercritical water, including heat transfer characteristics, pressure loss characteristics, flow stability issues, and numerical method. These works are mainly to give a basic idea of elementary but important topics in this area. An analytical method was proposed up to predict the heat transfer coefficient and friction coefficient based on the two-layer wall function. Flow instability experiments have been carried out in a two-parallel-channel system with supercritical water, aiming to provide an up-to-date knowledge of supercritical flow instability phenomena and initial validation data for numerical analysis. The natural circulation instability of supercritical water was also investigated in the experiments.