Surmet Engineering Better Material Solutions

Abstract: Aluminum Oxynitride (ALON® Optical Ceramic) combines broadband transparency with excellent mechanical properties. ALON’s cubic structure means that it is transparent in its polycrystalline form, allowing it to be manufactured by conventional powder processing techniques. Surmet controls every aspect of the manufacturing process, beginning with synthesis of ALON® powder, continuing through forming/heat treatment of blanks, ending with optical fabrication of ALON® windows. Surmet has made significant progress in its production capability in recent years. Additional scale up of Surmet’s manufacturing capability, for complex geometries, larger sizes and higher quantities, is underway. The requirements for modern aircraft are driving the need for conformal windows for future sensor systems. However, limitations on optical systems and the ability to produce windows in complex geometries currently limit the geometry of existing windows and window assemblies to faceted assemblies of flat windows. Surmet’s ability to produce large curved ALON® blanks is an important step in the development of conformal windows for future aircraft applications..
© 2015 SPIE. Window and Dome Technologies and Materials XIV, edited by Brian J. Zelinski, Proc. of SPIE Vol. 9453, 945306.

Abstract: Working closely with the University of Rochester, Surmet has developed gradient index (GRIN) optics in ALON for use in the visible through the MWIR applications. Surmet has demonstrated the ability to tailor the refractive index of ALON® Optical Ceramic by either varying its composition or through the addition of dopants. Smooth axial and radial gradient profiles with ~0.055 change in refractive index, over depths of 1-8 mm (axial) and over 20 mm radius (radial) have been demonstrated. Initial design studies have shown that such elements provide unique capabilities. Radial gradients in particular, with their optical power contribution, provide additional degrees of freedom for color correction in broadband imaging systems.
© 2016 SPIE Advanced Optics for Defense Applications: UV through LWIR, edited by Jay N. Vizgaitis, Bjørn F. Andresen, Peter L. Marasco, Jasbinder S. Sanghera, Miguel P. Snyder, Proc. of SPIE Vol. 9822, 98220V.

Abstract: ALON and spinel, two transparent ceramics used in IR optics, each exhibit a unique combination of properties; a comparison allows the optical engineer to select the right material for the job.
© Laser Focus World, Aug. 2014. All rights reserved.

Abstract: Production of aluminum nitride powder by direct nitridation or carbothermal reduction and nitridation requires balancing trade-offs between cost, carbon footprint, and properties.
© American Ceramic Society Bulletin, Vol. 93, No. 6. All rights reserved.

Abstract: Aluminum oxynitride and magnesium aluminate spinel are mechanically strong, hard and scratch resistant; they are also chemically durable. Both exhibit broadband transmittance from near-UV to mid-IR.
© Photonics Spectra, June 2014. All rights reserved.

Abstract: Polycrystalline ceramics with the cubic spinel structure enable multiple defense applications, including night-vision goggles and IR optics for military systems such as domes, lenses, reconnaissance and sensor windows – they also have applications in nonmilitary arenas such as semiconductor processing, oil and gas drilling, medical optics and lasers.
© Photonics Spectra, August 2013. All rights reserved.

Abstract: Aluminum Oxynitride (ALON® Optical Ceramic) combines broadband transparency with excellent mechanical properties. ALON’s cubic structure means that it is transparent in its polycrystalline form, allowing it to be manufactured by conventional powder processing techniques. Surmet has established a robust manufacturing process, beginning with synthesis of ALON® powder, continuing through forming/heat treatment of blanks, and ending with optical fabrication of ALON® windows. Surmet has made significant progress in our production capability in recent years. Additional scale up of Surmet’s manufacturing capability, for larger sizes and higher quantities, is currently underway. ALON® transparent armor represents the state of the art in protection against armor piercing threats, offering a factor of two in weight and thickness savings over conventional glass laminates. Tiled and monolithic windows have been successfully produced and tested against a range of threats. Large ALON® window are also of interest to a range of visible to Mid-Wave Infra-Red (MWIR) sensor applications. These applications often have stressing imaging requirements which in turn require that these large windows have optical characteristics including excellent homogeneity of index of refraction and very low stress birefringence. Surmet is currently scaling up its production facility to be able to make and deliver ALON® monolithic windows as large as ~19x36-in. Additionally, Surmet has plans to scale up to windows ~3ftx3ft in size in the coming years. Recent results with scale up and characterization of the resulting blanks will be presented
© 2011 Society of Photo-Optical Instrumentation Engineers (SPIE). All rights reserved.
Keywords: Ceramics; Domes; Manufacturing; Sensors; Optical fabrication

Abstract: The purpose of this first generation investigation is to evaluate the in vitro cytotoxicity, cell-materials interactions and tribological performance of spinel and ALON® transparent ceramics for potential wear applications. Besides their non-toxicity, the high surface energy of these ceramics significantly enhanced in vitro cell-materials interactions compared to bioinert commercially pure Ti as control. These transparent ceramics with high hardness in the range of 1334 and 1543 HV showed in vitro wear rate of the order of 10^-6 mm³ Nm^-1 against Al₂O₃ ball at a normal load of 22 N.
© 2011 Springer Science+Business Media, LLC 2011

Abstract: Performance of an Al–O–N based duplex coating system (DCS) was examined in order to improve the high-temperature oxidation resistance of superalloys and the low-pressure plasma sprayed NiCrAlY coatings. The DCS (~5 mm thick) was deposited using pulsed DC reactive magnetron sputtering as an external coating on Rene'N5 superalloy with and without NiCrAlY coating. DCS coatings were characterized using photo-stimulated luminescence spectroscopy, optical microscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy before and after high-temperature oxidation.
© 2003 Elsevier B.V. All rights reserved.
Keywords: Oxidation; Thermally grown oxide; Coatings; Residual stress; Photostimulate luminescence

Abstract: The optical properties of ALON (aluminum oxynitride) are presented. Optical scatter and index of refraction, and absorption of several different compositions of ALON are compared. The temperature dependence of emissivity of ALON was measured in the temperature range 46°C to 1200°C.
© 1998 Elsevier B.V. All rights reserved.
Keywords: ALON; aluminum oxynitride; Optical properties; Scatter; Spectral Emittance

Abstract: ALON® Optical Ceramic is a durable window material for UV, Visible and Mid IR window and dome applications. The mechanical, thermal, and optical properties of ALON products produced commercially by Surmet Corporation have been measured and this new data will be presented. Comparisons to previously measured data will be made. Optical quality, low scatter ALON having high strength that is nearly double previously reported has been made. Average strength values of 700 MPa at 21°C and 631 MPa at 500°C have been measured for ALON specimens prepared by precision surface finishing techniques. Polished optical domes tested have survived severe thermal shock tests. These strength levels are comparable to those for single crystal sapphire. Strength, thermal conductivity, thermal expansion, refractive index, emissivity and absorption coefficient will be presented. The possible mechanisms for the increased strength will be discussed.
Keywords: ALON, aluminum oxynitride, properties, strength, domes, transparent armor

Abstract: Durable coatings of silicon-carbon-oxy-nitride (a.k.a. SiCON) are being developed to protect high-speed missile windows from the environmental loads during flight. Originally developed at Rockwell Scientific Corporation (RSC) these coatings exhibited substantial promise, but were difficult to deposit. Under a DoD DARPA SBIR Phase I program, Surmet Corporation, working closely with RSC, is depositing these coatings using an innovative vacuum vapor deposition process. High rate of coating deposition and the ease of manipulating the process variables, make Surmet's process suitable for the deposition of substantially thick films (up to 30 μm) with precisely controlled chemistry. Initial work has shown encouraging results, and the refinement of the coating and coating process is still underway. Coupons of SiN and SiCON coatings with varying thickness on a variety of substrates such as Si-wafer, ZnS and ALON were fabricated and used for the study. This paper will present and discuss the results of SiN and SiCON coatings deposition and characterization (physical, mechanical and optical properties) as a basis for evaluating their suitability for high speed missile windows application. Keywords: Silicon-carbon-oxy-nitride (SiCON) Coatings, High speed missile windows, Plasma-enhanced CVD,

Abstract: Aluminum Oxynitride (ALON® Optical Ceramic) is a transparent ceramic material which combines transparency from the UV to the MWIR with excellent mechanical properties. ALON's optical and mechanical properties are isotropic by virtue of its cubic crystalline structure. Consequently, ALON is transparent in its polycrystalline form and can be made by conventional powder processing techniques. This combination of properties and manufacturability make ALON suitable for a range of applications from IR windows, domes and lenses to transparent armor. The technology for producing transparent ALON was developed at Raytheon and has been transferred to Surmet Corporation where it is currently in production. Surmet is currently selling ALON into a number of military (e.g., windows and domes) and commercial (e.g., supermarket scanner windows) applications.

hecapabilitytomanufacturelargeALONwindowsforbothsensorwindowandarmorapplicationsisinplace. ALON windows up to 20x30 inches have been fabricated. In addition, the capability to shape and polish these large and curved windows is being developed and demonstrated at Surmet. Complex shapes, both hyper-hemispherical and conformal, are also under development and will be described.
Key Words: Aluminum Oxynitride, ALON, MWIR windows, domes, ballistic armor

Abstract: New military requirements have reinvigorated the need for transparent magnesium aluminate (MgAl2O4) spinel. Surmet has developed a process that yields high quality transparent spinel at production scale. Several issues related to the extreme requirements of processing ultrafine spinel powders are described. Transmission data is presented for a significant dataset of parts made by this process.

More recently, the process has been expanded to include a capability for producing domes for the Joint Common Missile program. Domes at nominal 6” and 7” diameter have been successfully fabricated. Despite early challenges related to the forming portion of the process, a repeatable capability for these domes has been demonstrated.

Several challenges remain in spinel processing in order to support additional military requirements. In particular, the strength of the material needs further improvement. Also, improvements in optical quality with regard to inclusions are needed.

Keywords: spinel, MWIR windows, lenses, domes