An Inexpensive KBr Pellet Press Apparatus for preparing the KBr pellets used in ir spectroscopy range from 'A'' wrench-operated to those using hydraulic jacks' including versions equipped with a pressure gauge. We have used the inexpensive wrench-operated pellet presses and encountered the usual objections.' In an effort to obtain reproducible and good quality KBr pellets LC!PE:WON wa~arm and to reduce costs, we constructed the improved and inexpensive pellet press shown ..,.. .,...in the figure. The assembled apparatus readily fits into a hydraulic press. The camst,, pression chamber (center portion of the figure) which contains the prepared KBr pellet i-4 ,...- +, -1 fits a Wilks Instrument V-mount holder and is thus usable in most ir instruments. PLUNGE. The comolete nellet oress consists of two identical. 0.5-in. O.D. re~laceable p l u n ~ e r s r n w t m d(prt.i,l'tt~ina2-in. O.D. X I-In. rtainlessateel ba-tl haringaW>-in. punch-mr hde. The plungrriarr made inrm U.5-I". 0.1). No.903 Cleveland drill blank$ and project 0.5 in. from the bases. The plunger faces are ground lapped on wet or dry Carborundum paper (320 and 600 grit, respectively). A final highly-polished surface .. u a s ohtnmed u;i~~g nn alurn:nn puliihing c.mpuund. ... ... , 'I'he wmpreswm chamher runii.;t~of a rrplnrcnhle Acme, :32fi72 1'1.-18-12.0 5 in. I l ) . hradlrrs drill hushmr: liner. pressed inlo n stninlrsa s t 4 slervr 1.125 in. 0.1).X 0.73 in I.D. X 0.75 in. l m a h . We prefer the 2-in. diameter pi&ger base because this wider base provides better stability in the,hydraulic pr& and also orovides a fineer hold for seoaratine ., the oluneers . .. from the comoressian chamber after the KBr el let is .orenared. . 'I ,he p ~ u n ~ e r q kreadily rr withdraw). H~wever.shc>uld hey L I ~ frtven C ~ in T ~ cCt m p r r w m cha;nbrr, the). ran msdg be renwwd w:th a pair d wrtnche~m a wrench 3 r d vise. A s s h o ~ nin the fi,uurt.1181SKI*; haw hwn rnalhinrd, ti,r this purpuse, on the compression chamber and plunger bases. At 20,000 psig and using 60-100 mg of dry KBr, visually transparent and stable pellets are to be expected. The KBr pellet remains in the compression chamber during the spectroscopy run. This is a distinct advantage-since handling the pellet is avoided. Users are cautioned not to rotate the empty hut assembled apparatus to avoid scratching the plunger faces. After use, the KBr pellet is expelled and washed from the compression chamber. The entire apparatus is carefully dried and stored as separated pieces in a dry container. The plungers and compression chamber liner are not stainless steel and are subject t o corrosion and rusting. Approximately $20 in materials, described above, and 6 hr of machine work are required t o construct the pellet-press apparatus.
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Available from Wilks Infrared Center, South Norwalk, Conn. 06854 and Barnes Engineering Co., Stamford, Conn. 06902, respectively. Kletseh, R., J. CHEM. EDUC., 49,438 (1972). Leon F. P a h l e r Heinz Hall Edmund J. Eisenbraun Oklahoma State University Stillwater, OK 74074
~olurne56. Number 7, July 1979 1 447
