MAC 
 Standards

Reference Standards for X-Ray Microanalysis.

MAC manufacture standards for the following microanalysis systems: AUGER, BSED, EDX, SEM, STEM, TEM, WDX, XRF, and Microprobe. They  also manufacture Calibration standards for BSED and Scanning Electron Microscope (SEM).

We can produce standard blocks in several different materials, or sizes, to customers requirements. Carousels, 13mm dia. blocks to fit Pin stubs, and singles of 5mm, 3mm, 2mm in diameter are also available.
 

STAINLESS STEEL, BRASS, CARBON RESIN, ALUMINIUM.

The standards supplied are suitable for electron-beam Energy Dispersive or Wavelength Dispersive X-Ray microanalysis systems.

MAC only purchase reference samples from leading suppliers to ensure consistent high quality; the samples are fitted into brass blanks in our own modern factory; diamond polished to a 0.25mm carbon coated. Every single reference standard is tested with our own Analysis/SEM Equipment before shipping. This attention to detail has gained MAC a reputation for unsurpassed technical excellence during the past decade. Whilst MAC are uncompromising in their approach to quality, they also appreciate the importance of realistic delivery times and economical prices. MAC obtained certification to BS EN ISO 9002:1994 in April 1997.

All the standards are supplied with a certificate of analysis and a large number of the standard materials are traceable to a national institution, as a standard reference material (SRM).

Each block of standards has its own unique number allocated to it, and recorded, and comes with a map for standard identification. We have all of our records back to the first block of standards produced in 1981.

A Faraday Cup, for accurate specimen current measurements, is available as standard on some blocks, and as an optional extra on the others.

We have over 250 different standards material to choose from which include rare earth's, SRM's, Compounds and pure elements.

 

Materials
The materials used are the best available at the time of purchase

Source.
Material is obtained from a wide variety of sources from all over the world and is dependent on customers requirements and available price.  It is only obtained from bona-fide chemical and (SRM) standards material suppliers.  Where possible certificates of analysis and Safety Data Sheets are obtained.

All information regarding source of material, analysis & Safety Data Information is logged and kept on file indefinitely.  Data of receipt and date of usage is recorded.

Minerals.
Minerals are obtained from a variety of sources and suppliers.  Their original location being recorded.  The bulk material is split into two halves.  One half is then split into five lots of material and then sent to at least five University "Earth Science Laboratories" More than one type of analysis is employed i.e. Magnetite was analyzed using X-Ray diffraction, Energy Dispersive X-Ray analysis and ICPAES.  The results were checked against a known Magnetite sample.

Pure Metals.
Pure metals are obtained from suppliers in as pure a form as possible.  They range from:

Germanium (Ge) @ 100% pure
to
Hafnium (Hf) @ 97% Hf, 2.7% Zr with a range of impurities listed in PPM

Compounds
Compounds come in two categories:

1. Those which are supplied with certificates showing types of analysis used i.e. x-ray diffraction and Spectrographic analysis.
2. Those compounds where the analysis has been theoretically calculated.

Rare Earth's.
Rare Earth's are supplied with certificates of analysis and an indication of any difficulties experienced in the production of the material. i.e. inability to produce a single phase material.

Standard Reference Materials (SRM).
Material is obtained from NIST (formally NBS), MBH, ARMII, BCS & BAS EURO as Standard Reference Material. We can obtain material form other world standard sources as well. These suppliers obtain material from specialist producers all over the world and some of them have it reanalyzed to confirm the original analysis. This material is supplied with full analysis, tractability and homogeneity certification.

Registration Number.
Each order when received and confirmed is allocated a number. This number is recorded for ever at MAC. It is stamped on the base of all but the smallest single standards and at any time we can access our data base on the history of the order.

Preparation.
The materials are prepared and embedded in their blocks, usually in energy order, with epoxy resin or Woods metal. Block material can be either Brass, 304 Stainless Steel, Aluminium or Carbon Resin. The block size and shape is to the customers specification. The blocks are embedded inside a laminar flow cabinet fitted with filters. The epoxy resin suffers no shrinkage

Grinding.
The resin is left to set overnight. When dry the block is ground down on a series of wet and dry papers with careful washing and inspection at each stage.

Polishing.
After grinding the block is placed on an iron lapping plate, and a series of diamond paste form 14Ám, 6Ám to 3Ám are used on an automatic lapping machine with varying grades of cloths and nap to polish the block and standards on the same plane. In between each stage of polishing the block is washed in degreasing agent and examined optically to make sure that scratches remaining from previous grades have been removed, and that the standards are as flat as can be obtained within the confines of the different hardness of the materials being polished.

The final polishing stage is carried out by hand using experienced personnel, using 1Ám and 0.25Ám diamond paste. When the polishing stage is considered optically to be complete, the block is washed in an ultrasonic bath and coated with 10 to 20nm of Carbon. This is to reduce charging under the electron beam by making the surface conducting.

Optical, SEM, EDX check.
After coating above, the block of standards is checked for scratches impurities and standard of polish under a good optical microscope.
The block of standards is then transferred to the Scanning Electron Microscope (SEM) with Energy Dispersive X-Ray analyzer (EDX) and a spectrum is accumulated for 50 to 100 sec's on all standards material. Each peak is identified for correct KeV using the K, L and M X-Ray lines with and excitation potential on the electron gun of 15KV. Count rates of 2000 to 2500 cps are selected and the dead time is kept to a minimum i.e. less than 20%. Particular attention is paid to any artifacts that may be present. The block, if found to be OK is packed and shipped to the customer with a Registration numbered book containing Certificates of Analysis, location map, advice on the care of the block, signed test certificate and an estimated time for a re-polish and re-coat of Carbon. A copy of all this information is held at MAC for ever! A copy of the registered book can be obtained any time in the future.
We are able to trace all of our standards blocks back over the last 16 years to the first one produced by MAC and still provide certificates of analysis and layout plans for them. In order for us to supply the customer with the security that we can be as certain as possible that we know what material was used and where we obtained it from we were aware of the need to have a Quality Management System. In view of this we obtained certification to BS EN ISO 9002:1994 in April 1997 and are currently registered with National Quality Assurance Ltd. (NQA). Our certificate number is 8960. This attention to detail has gained MAC a reputation for unsurpassed technical excellence during the past 16 years.

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