Layer | Fill | Outline |
---|
Map layers
Theme | Visible | Selectable | Appearance | Zoom Range (now: 0) |
---|
Fill | Stroke |
---|---|
Collaborating Authors
Results
ABSTRACT ABSTRACT Aluminide coatings were applied by halide activated pack cementation to austenitic 304 stainless steel substrates. The evolution of coating microstructure as a function of coating process parameters, e.g., temperature, time, etc., was explored. Stainless steel type 304 was chosen as a model substrate to understand the kinetics of aluminizing and for the potential enhancement in high temperature corrosion resistance. The kinetics of the aluminizing process was studied at different temperatures in the 650 – 850°C range and times in the 1 – 25 h range. At 650°C, the coating consisted of a single layer containing two phases tentatively identified as Al5FeNi (Cr) as the matrix with a dispersed aluminide, Al86Fe14. At 850°C, the coatings initially consist of at least two layers containing three phases [with a preliminary identification as Al86Fe14, AlxFey(Ni,Cr) and Al5Fe Ni(Cr) which transitions to a single layer of possibly AlxFey(Ni,Cr) and intermetallic precipitates of undetermined composition. INTRODUCTION Stainless steels are known to have excellent resistance to attack from corrosive media at both room and elevated temperatures. High temperature corrosion is a potential problem for austenitic stainless steels, e.g., 304, used in chemical processing environments. Extension of the operating regime and the life of the base alloy can be achieved by the application of protective coatings. Aluminum-containing coatings form stable protective oxide scales, making aluminum a commonly used coating element and aluminizing a ubiquitous coating process. In the current study, the halide activated pack cementation process was used to apply aluminum diffusion coatings onto the surface of 304 SS. EXPERIMENTAL PROCEDURE Stainless steel samples were cut into 5 mm thick, 12.5 mm diameter coupons. The samples were then taken through standard metallographic preparation procedures by grinding the surface down to 600 grit using silicon carbide abrasive paper. Packs were prepared by mixing powders of aluminum oxide (“filler”), aluminum (“masteralloy”) and aluminum chloride (“activator”).
- Well Completion > Well Integrity > Subsurface corrosion (tubing, casing, completion equipment, conductor) (1.00)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Materials and corrosion (1.00)
- Production and Well Operations > Production Chemistry, Metallurgy and Biology > Corrosion inhibition and management (including H2S and CO2) (0.88)
Stability of Advanced Titanium Alloys In Saline Solution And Characterization of Osteoblast Activation
Ravi, Vilupanur A. (California State Polytechnic University) | Enriquez, Roviden (California State Polytechnic University) | Beecher, Carlos (California State Polytechnic University) | Razzak, Amina (California State Polytechnic University) | Chantrjaroen, Warintra (California State Polytechnic University) | Schissler, Andrew (California State Polytechnic University) | Malek, Mehnaz (California State Polytechnic University) | Surmenian, Daniel (California State Polytechnic University) | Priddy, Isaac (California State Polytechnic University) | Urak, Ryan (California State Polytechnic University) | Schooley, Amber (California State Polytechnic University) | Alas, Steve (California State Polytechnic University)
ABSTRACT ABSTRACT Electrochemical characterization of titanium alloys with different levels of boron was carried out in phosphate buffered saline (PBS) at body temperature and in 0.9 wt% sodium chloride (saline) at room temperature. Two types of cyclic potentiodynamic polarization tests were conducted - one based on ASTM F 2129-08 and the other with a broader voltage scan with higher peak potentials that further distinguished the behavior of the different titanium alloys. Break-down (pitting) potentials for the alloys in the latter test were in the 4.9 – 6.5 V range. The susceptibility of osteoblast cells to the titanium (IV) ions released from the different alloys during exposure to cyclic polarization tests was analyzed. The ion levels from the alloys, adjusted to synovial tissue levels, were not high enough to induce osteoblasts to undergo a destructive increase in apoptosis (programmed cell death). Additionally, the titanium alloys containing boron, induced the expression of the protein - receptor activator of nuclear factor kappa-B ligand (RANKL) - more than the alloys without boron. However, the critical level of RANKL expression necessary to activate osteoclast activity is still to be determined. INTRODUCTION The underlying cause of prosthetic loosening in patients whose implants have failed is the imbalance between osteoblast and osteoclast activity. Throughout an individual’s life, bone is constantly being replaced in order to maintain a durable skeleton. The process by which this occurs involves collaboration between bone degenerating cells, osteoclasts, and bone regenerating cells, osteoblasts. Osteoblast cells will activate osteoclasts to resorb existing bone. Afterwards, osteoblasts will replace the decalcified area with new bone, hence maintaining a healthy skeletal structure. However, if osteoclast activity is higher in the body than osteoblast activity, bone resorption outpaces bone generation and leads to bones becoming weak and fragile. This process is the primary reason for the development of osteoporosis in elderly individuals.
- North America > United States > Texas (0.19)
- North America > United States > California (0.15)
- Materials > Metals & Mining > Titanium (1.00)
- Health & Medicine (1.00)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Materials and corrosion (0.70)
- Well Completion > Well Integrity > Subsurface corrosion (tubing, casing, completion equipment, conductor) (0.48)
- Production and Well Operations > Production Chemistry, Metallurgy and Biology > Corrosion inhibition and management (including H2S and CO2) (0.48)