An Assessment of the National Institute of Standards and Technology Materials Science and Engineering Laboratory: Fiscal Year 2010 (2010)

The mission of the Materials Reliability Division is to develop and apply new measurement science to determine how, when, and why a material fails to perform as expected and to conduct research to help determine its operational limits during use. The division has seen slow but steady growth over the past 5 years, from 31 staff members in 2005 to 43 in 2010, including 17 permanent technical staff, 6 NRC postdoctoral researchers, 1 term employee/student, 17.4 associates, and 2 administrative positions (see footnote 1). At the same time, the division’s budget has grown from approximately $5.25 million to $8.6 million, with $370,000 coming from other agencies.

Three groups—Structural Materials, Nanoscale Reliability, and Cell and Tissue Mechanics—conduct the activities of the Materials Reliability Division. The programs of the Structural Materials Group are concerned with test methods to ensure materials reliability for structural applications. The programs of the Nanoscale Reliability Group are concerned with developing measurement methods to assess changes in the behavior of materials when dimensions approach the nanoscale. Finally, the Cell and Tissue Mechanics Group is developing measurement techniques targeted at the reliability of the interface between biological systems and biomaterials. Each group is engaged in three to four major projects.

The review, which extended over a day and a half, consisted of an overview of each group and then a more detailed presentation of at least two programs of the group.

The programs reviewed are of high technical quality. The relatively recent efforts related to cell biology are exciting and attracting external collaborators, and the classic Charpy test specimen program continues to enjoy strong industrial support.

The Materials Reliability Division is located at NIST’s Boulder, Colorado, site. Although the division’s principal building is old and marginally functional, the laboratories within are well equipped. The High Pressure Hydrogen Test Facility, completed in January 2010, and the Precision Measurements Laboratory, scheduled for completion in 2011, will facilitate the expansion of both structural materials and bio-related activities as well as provide unique precision imaging capabilities that will benefit all of the division’s programs. Most of the laboratories will remain in the main building, which suffers from periodic flooding and poor-quality electrical power.

As its budget had grown, the division has added staff. These include impressive early-career staff and outstanding NRC postdoctoral associates (see Box 3.1).

During the past 2 years (2008 and 2009), the staff of the Materials Reliability Division were responsible for 39 publications in peer-reviewed journals, 11 articles in refereed proceedings, 6 contributions to books, and 2 NIST Recommended Practice Guides. This is an appropriate publication record for this division. A single patent application was filed. Six staff have been honored by NIST Bronze Medal awards (3 in 2008 and 3 in 2009), and several Distinguished Associates Awards were presented each year.

The objectives of the division’s research projects are clearly defined, and the work reviewed is consistent with the project plans.

The Structural Materials Group has core competencies in macroscale mechanical testing and in developing standard testing procedures and reference materials that are important to the reliability of the nation’s infrastructure. The group has responsibility for four projects and is composed of six permanent technical staff, two NRC postdoctoral researchers, and 8.7 associates (see footnote 1), who exhibit a high level of competence and dedication to meeting critical infrastructure needs. Investments made since 2008 have enhanced the group’s testing and measurement resources, thereby maintaining capabilities that are among the best in the world, and in some cases, unique. The programs and project reviewed for this assessment are the Charpy Verification Program, the Pipeline Safety Program, and the Physical Infrastructure Project.

Since the previous review, numerous upgrades to the test capabilities of the Structural Materials Group have been made. High-bay tensile and fatigue in addition to Charpy testing capabilities have been upgraded with new hydraulic flow systems, load frames and controllers that expand the load range from 20 kN to 4.5 MN, increase temperature capabilities from -269ºC to 1,000ºC, and increase crack growth rates up to

5 m/s. For large-scale tensile testing, temperatures can be maintained from -60ºC to 250ºC. Although not installed, a new 55 kip load frame has been purchased. The group’s testing capabilities were also enhanced by the recent commissioning of the world’s most advanced high-pressure hydrogen test facility, capable of operating at pressures approaching 140 MPa.

The Charpy Standard Reference Materials (SRMs 2092, 2096, and 2098) continue to play a vital role in validating Charpy impact machines used to qualify steels employed in construction. Annually, the program evaluates specimens from testing on more than 1,000 machines to ensure that national and international standards are maintained for high-impact energy tests and supplies more than 10,000 certified SRMs for verification of acceptance tests. The Charpy Verification Program has been a traditional pillar of the Materials Reliability Division, and it continues to serve vital national needs while remaining innovative in seeking ways to improve its capabilities. In response to the higher-strength steels being developed, an ultrahigh-load-capacity (700 J) Charpy test machine has recently been commissioned. To serve the program’s customers better, a laser scanning system is now used to document notch characteristics more precisely, increasing the sensitivity to detecting roughness at the notch. Better environmental control (temperature and humidity) has been achieved in the Charpy test laboratory with the installation of a dedicated heating, ventilating, and air-conditioning system.

The Pipeline Safety Program has developed unique capabilities for testing large pipeline sections that are more than 2 m long, while creating a uniform strain field over more than 1 m. Current testing of 2-m-long by 0.3-m-wide curved plates at up to 4.5 N and temperatures as low as -60ºC is producing unique fracture resistance data. A high-speed camera system has been integrated into the Crack Tip Opening Angle test system for stop-frame imaging of cracks approaching actual pipeline rupture conditions. This work involves external collaborators, who are developing three-dimensional crack-propagation models in order to validate test methods and establish design criteria. Activities also include the development of a facility to test fracture behavior in pipelines that transfer corrosive biofuels and fuel blends. The extensive in-house testing conducted by the Pipeline Safety Program is meeting the needs of numerous industrial customers and partners.

With the completion of the hydrogen test facility, the Hydrogen Storage and Transport project is beginning work on standardizing methods for high-pressure testing, acquiring critical materials data, and establishing codes for material behavior and selection.

The Physical Infrastructure Project is motivated by the growing cost of infrastructure rehabilitation. There is a pressing national need to assess aging

infrastructure for its reliability quickly and reliably. These assessments will benefit from new measurement tools and methods. This project is directed toward the development of measuring techniques that will reduce the error and uncertainty associated with the inspection of existing bridges. To this end, the project is qualifying new sensors, some of which may be embedded in a bridge’s structure. A necessary step in the development of these sensors has been taken with a new acoustic emission calibration block facility, which is used to calibrate new acoustic emission sensors.

The panel’s finding and recommendation regarding the Structural Materials Group are as follows:

Finding: Overall, the personnel of the Structural Materials Group are productive and meeting important national needs.

Recommendation: Productivity and impact would be enhanced by the addition of two new staff members—one a materials scientist to delve more deeply into fundamental aspects of the test results, and the other a technician dedicated to large-scale testing activities in the high-bay facility.

The mission of the Nanoscale Reliability Group is to address physical mechanisms that dictate reliability when material and device dimensions are constrained in the nanoscale regime and to develop test methods, instrumentation, and models to measure material performance directly in complex device geometries and under in-use conditions in order to interpret size effects fully. The group has responsibility for three major projects. It is composed of seven permanent technical staff, two NRC postdoctoral researchers, and four NIST associates (see footnote 1). Postdoctoral research in the Nanoscale Reliability Group involves the innovative assessment of viscoelastic properties using contact resonance force microscopy and failure processes of carbon nanotubes under fatigue. The projects reviewed are these: Interconnect Reliability, Atomic Force Microscopy (AFM)-Based Nanomechanics, and Microsystems for Harsh Environments.

The incorporation of a theorist is helping with the design of testing methods based on the modeling of electrical and thermal stress distributions. Cyclic thermal lifetime by resistance heating is a clever simulation of industrial significance to the semiconductor industry. Potentially, this could become an industry standard for the quality control of next-generation conduction pathways on a chip, as the test being developed does not require specialized test specimens. The electrical resistance fatigue instrument has been developed specifically for testing at the nanometer scale and could be available as a commercial interconnect screening technology. The instrument is beyond the state of the art and meets an important commercial need, as demonstrated by interest from Novellus

Systems, Inc., which is collaborating with NIST on utilizing this method to detect failures in copper interconnect lines.

An effort using contact resonance measurements to make measurements on buried interfaces has both linear and nonlinear potential for measuring extremely small scale responses of importance to the architectural design of microelectromechanical systems (MEMS) and nanoelectromechanical systems (NEMS) devices, nanocomposites, microelectronic devices, and other thin films and nanostructures.

The development of the contact-resistance force microscopy (CR-FM) imaging technique under the Atomic Force Microscopy-Based Nanomechanics project is relatively mature, but the detection of buried interfaces was initiated as a new direction for this work in late 2009. CR-FM couples an acoustic AFM method with NIST-developed electronics for high-speed imaging, enabling measurements of the relative stiffness and moduli of buried interfaces—an advance in the state-of-the-art technology. The method and associated electronics for this project are finding a variety of applications, including the characterization of interphases, buried defects, nanostructures, polymer blends, and thin-film adhesion.

The Nanoscale Reliability Group is collaborating with other MSEL projects (Exploratory Research Grant, and Innovation in Measurement Science). A commercial AFM company has already invested in the electronics as a potential upgrade to its devices.

As nuclear reactors are relicensed, test methods are needed to ensure their reliability near the end of their design lifetimes. Since the volume of potential test material exposed to these harsh environments for 40 years is dwindling, the need to better utilize the remaining test specimens is critical. NIST is evaluating the use of small-scale test structures to provide rapid testing of statistically relevant samples stored in harsh environments. If focused ion beam and micro-electro-discharge-machining techniques for the sectioning of specimens can be developed, a statistical database can be developed in a short time with minimal material.

The panel’s findings and recommendations for the Nanoscale Reliability Group are as follows:

Finding: The Nanoscale Reliability Program is poised to launch several innovative and consequential techniques that would benefit both its basic and applied goals. Both science-based and commercial opportunities were quite apparent and to some degree have already formed. The research base exists but is subcritical in size to exercise its potential sufficiently.

Recommendation: Greater collaboration should be pursued with university-based modeling efforts in order to reach full potential. A particularly appropriate avenue for collaboration would be to involve a recognized authority on Green’s functions and thereby to coordinate efforts between the Nanoscale Reliability Group’s experimentalists and university-based multiscale-modeling efforts.

Finding: The recent hire for the Nanoscale Reliability Group addresses one of the findings by the NRC panel that reviewed the laboratory in 2008: that finding stated that new hires were essential.

Recommendation: The incremental productivity increase provided through another hire or two to this group should catalyze substantial program growth. Emphasis should be given to proposal writing. Successful proposals would be beneficial in improving the program.

The Cell and Tissue Mechanics Group is composed of three permanent technical staff, two postdoctoral researchers, and 4.7 associates (see footnote 1). The group’s mission is the development of measurement techniques to assess the reliability of biomaterials. Here reliability is seen to occur at the interface between biological systems and synthetic (bio) materials where the interaction between the biological system and the biomaterial can cause failure of one or both. Hence, developing measurement techniques to determine properties at the interface between tissues and biomaterials is a key component of this group’s focus.

The group has responsibility for four projects: Medical Device Reliability, Instrumented Bioreactor, Cell Platforms for Quantifying Nano/Bio Interactions, and Resonating Platforms for Nanomaterial Analysis. This fourth project also includes efforts to characterize carbon nanotubes in collaboration with researchers in MSEL and the Physics Laboratory. The projects reviewed are these: Medical Device Reliability, Instrumented Bioreactors, Cell Platforms for Quantifying Nano/Bio Interactions, and Resonating Platforms for Nanomaterial Analysis.

The Instrumented Bioreactor project is aimed at improving the mechanical durability for cartilage replacement and other load-bearing applications. Thus for optimizing hydrogel-based engineered tissues, the project has developed ultrasonic sensors to be incorporated for monitoring extracellular matrix content, and electrochemical sensors have been developed to measure metabolic activity. This technology is being used to advance hydrogel-based cartilage replacement.

This project involves novel instrumentation for measurements important to industrial biochemistry.

The Cell Platforms for Quantifying Nano/Bio Interactions and the Resonating Platforms for Nanomaterial Analysis projects of the Cell and Tissue Mechanics Group are intended to create methods useful in the evaluation of biocompatibility and toxicity of nanoparticles. The increasing use of nanomaterials and their potential proliferation in the environment motivate these projects. The environmental, health, and safety effects that arise from the unique dimensional characteristics (e.g., size, shape, aspect ratio) and properties (e.g., composition, surface chemistry, charge, reactivity) of these materials are not well understood, in part because of a lack of standardized methods for evaluating their toxicological consequences.

These projects are outgrowths from prior work on three-dimensional tissue scaffolds, which is now being developed as a testbed to evaluate nanotoxicity in a three-dimensional tissue engineering hydrogel scaffold in the presence of neural cells. This scaffold provides an environment in which cell response to nanoparticles can be measured for weeks, without the expense associated with in vivo assays or the short-term limitations of biochemical assays. A systematic approach is focused on evaluating the nanoparticle distribution and concentration within the hydrogel, which will then form a framework for the evaluation of the dose effects and potential for changes in evaluating the long-term stability of the nanomaterials.

A new technique using resonating platforms for nanomaterial analysis has been developed to evaluate properties of a few carbon nanotubes. This technique, developed in-house, appears to be a very good addition to their capabilities. Once the carbon nanotubes can be characterized and sorted according to critical dimensions, their interaction/reaction can be rapidly screened using a new instrument based on the quartz crystal microbalance.

To be able to develop certified reference materials, a separate project at the Gaithersburg, Maryland, facility is developing methods to produce well-characterized carbon nanotube suspensions. The careful control of parameters (length, type, charge, concentration, and impurities) will rely on the development of techniques to characterize these properties using small amounts of suspensions. Methods are being evaluated to ensure consistency among the carbon nanotubes used in the toxicity screening.

The panel’s finding and recommendation for the Cell and Tissue Mechanics Group are as follows:

Finding: The Cell and Tissue Mechanics Group is young but poised to respond to an important and growing national need.

The equipment seems adequate for the project, although cramped in the current space. It is noted that the group has allocated a larger laboratory and will be relocating

shortly. Laboratory access on upper floors is a concern as there is currently no elevator to transport supplies, including cryogenic fluids and gases.

Recommendation: The design and installation of an elevator to service the group’s laboratory should be expedited.

In general, the Materials Reliability Division is in excellent shape and has addressed the issues identified by the 2008 NRC review panel. The projects reviewed in the present assessment are focused on the mission of the MSEL and build effectively on the historic strength of the division in mechanical testing for reliability. The research distribution among the three division groups is close to ideal. There is an excellent mix of established (Structural Materials Group), maturing (Nanoscale Reliability Group), and nascent (Cell and Tissue Mechanics Group) research projects, which is indicative of the attempt to anticipate national needs. Such a mix also helps to ensure division vitality well into the future.

The division has developed several noteworthy measurement tools and devices that have the potential to enhance greatly the competitive position of different segments of the U.S. industry. However, as indicated in the panel’s findings and recommendations, there are areas that could use improvement.

Finding: The Materials Reliability Division’s staff member publication rate is low. A division of this size should target 35 to 50 publications per year in reputable journals.

Recommendation: Publications should be encouraged not simply for the sake of numbers, but because the work merits publication. A higher publication rate has the added advantage of lowering the barrier to proposal submission—an absolute necessity if the division is to grow.

Finding: Several technologies appear to be eligible for patent protection and licensing. The level of interest and awareness of patenting within the division was relatively low.

Recommendation: A strong and consistent policy regarding intellectual property should be developed.

Finding: Extensive collaborations of division staff on the Boulder, Colorado, campus with MSEL in Gaithersburg, Maryland, were not apparent.

Recommendation: To the extent that the panel’s perception of the level of collaboration between the MSEL components in Boulder and Gaithersburg is accurate, steps should be taken to leverage the expertise of the NIST laboratories as a whole.

Finding: Several of the staff members and division leadership expressed the need for outreach to other national laboratories or universities to partner joint proposals. This observation underlined the self-recognized weaknesses in generating peer-reviewed publications. In this respect the strengths of the Nanoscale Reliability Program are highlighted.

Recommendation: Sufficient resources should be added to facilitate this outreach. The resources could be in the form of additional staff or technical support personnel who would free up time for the necessary outreach. Attracting more postdoctoral associates might also facilitate outreach. Either way, this effort could pay dividends in terms of publications (recognition) and greater success at generating soft funding (proposal success).

Finding: Failing of the infrastructure and physical plant is leading to frustration and lower productivity. Flooding, in particular, has repeatedly led to experimental downtime. However, the construction underway to improve the nanofabrication facility is a very positive event. This facility will house various Raman, atomic force microscopy, and transmission electron microscopy improvements in instrumental capabilities.

Recommendation: Laboratory access (the elevator noted in the earlier recommendation for the Cell and Tissue Mechanics Group) and necessary maintenance, including the refurbishing of the older physical plant, need be provided as soon as possible.

Finding: NRC postdoctoral associates were knowledgeable and excited about their projects, with unique proposal ideas that continue to evolve. However, there were inconsistencies in the mentoring of the postdoctoral associates. In addition, there was a general desire among these postdoctoral associates for a more stimulating and scholarly environment of the type that most experienced during their postgraduate education.

Recommendation: The division, and perhaps the entire Boulder facility, should undertake a review of the postdoctoral experience and support efforts to build a postdoctoral community, establish mentoring guidelines, and establish programs to “market” NIST postdoctoral associates to the broader scientific community. (See Box 3.2 below.)