To improve the microstructure and mechanical properties of fundamental materials including aluminum, stainless steel, superalloys, and titanium alloys, traditional manufacturing techniques have for years been utilized in critical sectors including the aerospace and nuclear industries. However, additive manufacturing has become an efficient and effective means for fabricating these materials with superior mechanical attributes, making it easier to develop complex parts with relative ease compared to conventional processes. The waste generated in additive manufacturing processes are usually in the form of powders, while that of conventional processes come in the form of chips. The current study focuses on the features and uses of various typical recycling methods for traditional and additive manufacturing that are presently utilized to recycle material waste from both processes. Additionally, the main factors impacting the microstructural features and density of the chip-unified components are discussed. Moreover, it recommends a novel approach for recycling chips, while improving the process of development, bonding quality of the chips, microstructure, overall mechanical properties, and fostering sustainable and environmentally friendly engineering.

Fatigue behavior of woven melt infiltrated (MI) SiC/SiC ceramic matrix composites (CMCs) was investigated under a tension–tension fatigue condition in a combustion environment. A special experimental facility is designed to subject the CMCs under simultaneous mechanical and combustion conditions which is more representative of some conditions experienced by the hot section components of a jet engine. The MI SiC/SiC CMCs considered in this study consists of a SiC matrix densified with liquid Si infiltration, BN interphase, and reinforced with two different fibers, namely, Hi–Nicalon type S and Tyranno SA fibers. A high velocity oxygen fuel (HVOF) gun is used to create the representative combustion condition and a horizontal hydraulic MTS machine to apply the mechanical loading. Several fatigue tests were conducted at different stress levels with a stress ratio of 0.1, frequency of 1 Hz, and the specimen surface temperature at 1200 °C. Similar tests were conducted in an isothermal furnace condition at 1200 °C for comparison. Electrical resistance (ER) was used to monitor the tests. A reduction in the fatigue life was observed for the two MI systems under combustion conditions in comparison to the isothermal furnace condition at the same applied stress level. This is attributed to the presence of harsh combustion environment present in the burner rig. ER showed some promising results in monitoring the temperature and detecting damage in the specimen. Runout condition was set as 24 H (86400 cycles) in burner rig and 100 H (360000 cycles) in furnace environment. Specimens that achieved the runout condition were subsequently tested under monotonic tension testing at room temperature after cooldown to evaluate the residual properties. Residual strength results showed a significant strength reduction in both the furnace and burner rig environments. Post-test microscopy was conducted on the fracture surfaces of the failed specimens to understand the oxidation behavior and damage mechanisms.

The method of direct current potential drop (DCPD) can be utilized as an effective and convenient approach for in situ damage detection, and as a nondestructive evaluation technique. We present the results from use of a multiprobe DCPD technique for in situ damage detection in loading of a SiC/SiC composite. It is shown that in three different modes of loading (monotonic, fatigue, and cyclic load–unload), the sensing capabilities of DCPD technique compare well to the techniques of modal acoustic emission (AE) and digital image correlation (DIC). It was also found that DCPD technique provides a far earlier warning of failure under fatigue loading than the other two methods. In addition, we show that strategically placed multiple voltage leads on the specimen surface provide a promising way of qualitatively determining the crack initiation site. Therefore, the use of multiple lead DCPD method, together with other techniques, provides a viable option for sensing damage in ceramic matrix composites (CMCs) with complex geometries, and for applications at higher temperatures.

Design thresholds for gas turbine engines are constantly pushed to improve performance. One aspect of design improvement is the reduction of weight in rotating components. Specifically, the inserted airfoil and disk combinations more often seen in legacy fleets are seldom preferred to integrally bladed rotors (IBRs) which weigh significantly less. Despite the tremendous performance

Grinding of tungsten carbide with cobalt binder (WC-Co) requires a high amount of energy input for a low material removal rate (MRR) resulting in a high tendency for surface damage. Further reducing WC-Co grind productivity is frequent stoppages of the process for dressing to remove cobalt (Co) binder adhering to the abrasive. This proof-of-concept sought to solve all these problems through laser assisted machining (LAM). Laser parameters in this work were selected to impart sufficient energy to melt Co binder without impacting the WC lattice. Subsequent grinding in the heat affected zone (HAZ) was done defect-free at 7.6 mm³/min/mm. Nonirradiated samples were damaged at a fraction of this MRR. This was possible because binder melting and re-solidification reduced yield strength and improved ductility under load. Grazing Incidence X-ray Diffraction (GIXRD) confirmed full recovery of the original WC-Co structure under the HAZ. This work has the potential to significantly improve productivity machining WC-Co through laser assisted near net shape rough grinding.